diff --git "a/Week1_\341\204\207\341\205\251\341\206\250\341\204\211\341\205\263\341\206\270\341\204\200\341\205\252\341\204\214\341\205\246_\352\271\200\352\260\200\354\230\201.ipynb" "b/Week1_\341\204\207\341\205\251\341\206\250\341\204\211\341\205\263\341\206\270\341\204\200\341\205\252\341\204\214\341\205\246_\352\271\200\352\260\200\354\230\201.ipynb"
new file mode 100644
index 0000000..0f67597
--- /dev/null
+++ "b/Week1_\341\204\207\341\205\251\341\206\250\341\204\211\341\205\263\341\206\270\341\204\200\341\205\252\341\204\214\341\205\246_\352\271\200\352\260\200\354\230\201.ipynb"
@@ -0,0 +1,4585 @@
+{
+  "nbformat": 4,
+  "nbformat_minor": 0,
+  "metadata": {
+    "colab": {
+      "provenance": []
+    },
+    "kernelspec": {
+      "name": "python3",
+      "display_name": "Python 3"
+    },
+    "language_info": {
+      "name": "python"
+    }
+  },
+  "cells": [
+    {
+      "cell_type": "markdown",
+      "source": [
+        "# **1주차 복습과제**\n",
+        "- 1주차 복습과제는 **넘파이/판다스 연습문제**입니다.\n",
+        "- 코드 작성하시고, 출력 결과까지 나오도록 실행 부탁드립니다.\n",
+        "  - 제출 시 파일명 본인 이름으로 변경해 주세요. ex) Week1_복습과제_OOO\n",
+        "- 교재에서 다루지 않은 메소드도 다수 포함되어 있지만 구글링이나 챗지피티 등을 활용해서라도 풀어주세요! 한 번씩 사용해 보면 좋을 것 같아 어려워도 문제에 포함했습니다 🤗"
+      ],
+      "metadata": {
+        "id": "jkGNNJY3S65Z"
+      }
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "## **넘파이**"
+      ],
+      "metadata": {
+        "id": "WedDHAHPJPIA"
+      }
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 1. Import the numpy package under the name `np`."
+      ],
+      "metadata": {
+        "id": "7Ue21e0fKFRI"
+      }
+    },
+    {
+      "cell_type": "code",
+      "execution_count": 11,
+      "metadata": {
+        "id": "60ACXMoSGe0H"
+      },
+      "outputs": [],
+      "source": [
+        "import numpy as np"
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 2. Print the numpy version and the configuration.\n",
+        "\n",
+        "(hint: `np.__version__`, `np.show_config`)"
+      ],
+      "metadata": {
+        "id": "FnHQOUj-KNiT"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "print(np.__version__)\n",
+        "np.show_config()"
+      ],
+      "metadata": {
+        "id": "FgXzYXoRS-V7",
+        "collapsed": true,
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "dd4f0adb-510a-42c5-9196-c8abcccb99c6"
+      },
+      "execution_count": 12,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "2.1.3\n",
+            "Build Dependencies:\n",
+            "  blas:\n",
+            "    detection method: pkgconfig\n",
+            "    found: true\n",
+            "    include directory: /opt/_internal/cpython-3.13.0/lib/python3.13/site-packages/scipy_openblas64/include\n",
+            "    lib directory: /opt/_internal/cpython-3.13.0/lib/python3.13/site-packages/scipy_openblas64/lib\n",
+            "    name: scipy-openblas\n",
+            "    openblas configuration: OpenBLAS 0.3.27  USE64BITINT DYNAMIC_ARCH NO_AFFINITY\n",
+            "      Haswell MAX_THREADS=64\n",
+            "    pc file directory: /project/.openblas\n",
+            "    version: 0.3.27\n",
+            "  lapack:\n",
+            "    detection method: pkgconfig\n",
+            "    found: true\n",
+            "    include directory: /opt/_internal/cpython-3.13.0/lib/python3.13/site-packages/scipy_openblas64/include\n",
+            "    lib directory: /opt/_internal/cpython-3.13.0/lib/python3.13/site-packages/scipy_openblas64/lib\n",
+            "    name: scipy-openblas\n",
+            "    openblas configuration: OpenBLAS 0.3.27  USE64BITINT DYNAMIC_ARCH NO_AFFINITY\n",
+            "      Haswell MAX_THREADS=64\n",
+            "    pc file directory: /project/.openblas\n",
+            "    version: 0.3.27\n",
+            "Compilers:\n",
+            "  c:\n",
+            "    commands: cc\n",
+            "    linker: ld.bfd\n",
+            "    name: gcc\n",
+            "    version: 10.2.1\n",
+            "  c++:\n",
+            "    commands: c++\n",
+            "    linker: ld.bfd\n",
+            "    name: gcc\n",
+            "    version: 10.2.1\n",
+            "  cython:\n",
+            "    commands: cython\n",
+            "    linker: cython\n",
+            "    name: cython\n",
+            "    version: 3.0.11\n",
+            "Machine Information:\n",
+            "  build:\n",
+            "    cpu: x86_64\n",
+            "    endian: little\n",
+            "    family: x86_64\n",
+            "    system: linux\n",
+            "  host:\n",
+            "    cpu: x86_64\n",
+            "    endian: little\n",
+            "    family: x86_64\n",
+            "    system: linux\n",
+            "Python Information:\n",
+            "  path: /tmp/build-env-v_9b5grh/bin/python\n",
+            "  version: '3.13'\n",
+            "SIMD Extensions:\n",
+            "  baseline:\n",
+            "  - SSE\n",
+            "  - SSE2\n",
+            "  - SSE3\n",
+            "  found:\n",
+            "  - SSSE3\n",
+            "  - SSE41\n",
+            "  - POPCNT\n",
+            "  - SSE42\n",
+            "  - AVX\n",
+            "  - F16C\n",
+            "  - FMA3\n",
+            "  - AVX2\n",
+            "  not found:\n",
+            "  - AVX512F\n",
+            "  - AVX512CD\n",
+            "  - AVX512_KNL\n",
+            "  - AVX512_KNM\n",
+            "  - AVX512_SKX\n",
+            "  - AVX512_CLX\n",
+            "  - AVX512_CNL\n",
+            "  - AVX512_ICL\n",
+            "\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 3. Create a null vector of size 10.\n",
+        "\n",
+        "#### ✅ 출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]\n",
+        "```\n",
+        "\n"
+      ],
+      "metadata": {
+        "id": "0lB5hLlTKb1Z"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.zeros(10)\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "eK4DTjPwS_zU",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "5bd10f54-4450-484c-8667-bbcc60c57ef9"
+      },
+      "execution_count": 13,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 4. Create a null vector of size 10 but the fifth value which is 1.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[0. 0. 0. 0. 1. 0. 0. 0. 0. 0.]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "7lSSfwh6Kj5v"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.zeros(10)\n",
+        "a[4] = 1\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "ofohgzsTTBs6",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "30e62097-70b1-4db6-b24d-5a87e530c799"
+      },
+      "execution_count": 14,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[0. 0. 0. 0. 1. 0. 0. 0. 0. 0.]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 5. Create a vector with values ranging from 10 to 49.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33\n",
+        " 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "-NeqvmpLKkdY"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.arange(10, 50)\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "oQ1Mo5W9TC0P",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "c0b88910-a141-43df-ae9d-73d904e10ad0"
+      },
+      "execution_count": 15,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33\n",
+            " 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 6. Reverse a vector (first element becomes last).\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[9 8 7 6 5 4 3 2 1 0]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "B1dFQzRNLN23"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.arange(10)\n",
+        "a = a[::-1]\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "wrpNYd4jTDsx",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "7c7a108f-f717-4f67-a30b-350d44fe4948"
+      },
+      "execution_count": 16,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[9 8 7 6 5 4 3 2 1 0]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 7. Create a 3x3 matrix with values ranging from 0 to 8.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[[0 1 2]\n",
+        " [3 4 5]\n",
+        " [6 7 8]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "doUDUe_NLOhe"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.arange(9).reshape(3, 3)\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "4g8WetkATEnw",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "90f967d5-d486-417f-acda-6bbd98d55f5f"
+      },
+      "execution_count": 17,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[0 1 2]\n",
+            " [3 4 5]\n",
+            " [6 7 8]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 8. Find indices of non-zero elements from [1,2,0,0,4,0].\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "(array([0, 1, 4]),)\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "s-MtSq2RLzJx"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.array([1, 2, 0, 0, 4, 0])\n",
+        "print(np.nonzero(a))"
+      ],
+      "metadata": {
+        "id": "jw9iUP7sTL7D",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "7b24015d-cee6-4b60-b8fb-a14f5dabdf95"
+      },
+      "execution_count": 18,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "(array([0, 1, 4]),)\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 9. Create a 3x3 identity matrix.\n",
+        "\n",
+        "(hint: `np.eye`)\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[[1. 0. 0.]\n",
+        " [0. 1. 0.]\n",
+        " [0. 0. 1.]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "ihRWHFUxL6ak"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.eye(3)\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "fFzDGJT5TNh7",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "d1515ab1-a627-423c-aa6c-9e7f0adaacec"
+      },
+      "execution_count": 19,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[1. 0. 0.]\n",
+            " [0. 1. 0.]\n",
+            " [0. 0. 1.]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 10. Create a 3x3x3 array with random values.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[[[0.30742852 0.26458726 0.85474383]\n",
+        "  [0.80234531 0.76268902 0.91286677]\n",
+        "  [0.8804109  0.51011378 0.82103555]]\n",
+        "\n",
+        " [[0.403753   0.83120234 0.15202655]\n",
+        "  [0.75782685 0.0732058  0.48148689]\n",
+        "  [0.2089428  0.44968622 0.88134184]]\n",
+        "\n",
+        " [[0.52251191 0.10738374 0.86279648]\n",
+        "  [0.26203911 0.42157754 0.68856833]\n",
+        "  [0.58133626 0.31059127 0.71354172]]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "FvkGsY8eLPCG"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.random.random((3, 3, 3))\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "084SAfnwTPpt",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "f240246d-31d4-4e01-f515-58e100ab068a"
+      },
+      "execution_count": 20,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[[0.03593104 0.2353642  0.5445187 ]\n",
+            "  [0.25584542 0.91390591 0.00562641]\n",
+            "  [0.9930815  0.66159525 0.22517526]]\n",
+            "\n",
+            " [[0.60797016 0.01061487 0.311095  ]\n",
+            "  [0.71896739 0.70443172 0.57885033]\n",
+            "  [0.08264436 0.00170929 0.0944805 ]]\n",
+            "\n",
+            " [[0.81116459 0.8830158  0.87981388]\n",
+            "  [0.81963238 0.63595265 0.39136283]\n",
+            "  [0.05696045 0.00421298 0.45956177]]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 11. Create a 10x10 array with random values and find the minimum and maximum values.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "0.018360924693465508 0.9990506368595156\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "4-VynNt5MVYY"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.random.random((10, 10))\n",
+        "print(a.min(), a.max())"
+      ],
+      "metadata": {
+        "id": "W14PP5x6TRh6",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "832fb69b-06b6-4dc7-fd80-86faf4f2909b"
+      },
+      "execution_count": 21,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "0.0028190672459244004 0.9971531844150502\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 12. Create a random vector of size 30 and find the mean value.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "0.46249036320403636\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "cQKXmfJBMVQ_"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.random.random(30)\n",
+        "print(a.mean())"
+      ],
+      "metadata": {
+        "id": "FS6ggiNJTStp",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "77810321-74c1-42af-b617-f9a3be6cf6e9"
+      },
+      "execution_count": 22,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "0.4403328346470911\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 13. Create a 2d array with 1 on the border and 0 inside. (size: 10x10)\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[[1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+        " [1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "QZ4h-AddMVJb"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.ones((10, 10))\n",
+        "a[1:-1, 1:-1] = 0\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "pKEi08edTUMt",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "d574e92d-6d8e-46b1-a930-7eda829ef789"
+      },
+      "execution_count": 23,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
+            " [1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 14. How to add a border (filled with 0's) around an existing array?\n",
+        "\n",
+        "(hint: 인덱싱 사용)\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "# before\n",
+        "[[1. 1. 1. 1. 1.]\n",
+        " [1. 1. 1. 1. 1.]\n",
+        " [1. 1. 1. 1. 1.]\n",
+        " [1. 1. 1. 1. 1.]\n",
+        " [1. 1. 1. 1. 1.]]\n",
+        "\n",
+        " # after\n",
+        " [[0. 0. 0. 0. 0.]\n",
+        "  [0. 1. 1. 1. 0.]\n",
+        "  [0. 1. 1. 1. 0.]\n",
+        "  [0. 1. 1. 1. 0.]\n",
+        "  [0. 0. 0. 0. 0.]]\n",
+        "\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "BIwX-BiSMUz_"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.ones((5, 5))\n",
+        "print(\"# before\")\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "A4M1huiqTWXy",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "75f8ee17-f5c0-4e67-cc4f-c26d1db19a0b"
+      },
+      "execution_count": 24,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "# before\n",
+            "[[1. 1. 1. 1. 1.]\n",
+            " [1. 1. 1. 1. 1.]\n",
+            " [1. 1. 1. 1. 1.]\n",
+            " [1. 1. 1. 1. 1.]\n",
+            " [1. 1. 1. 1. 1.]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "b = np.zeros((7, 7))\n",
+        "b[1:-1, 1:-1] = a\n",
+        "print(\"# after\")\n",
+        "print(b)"
+      ],
+      "metadata": {
+        "id": "idWhL4zzTWRO",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "43563928-7ce9-4d07-c193-ffcbe3fc4853"
+      },
+      "execution_count": 25,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "# after\n",
+            "[[0. 0. 0. 0. 0. 0. 0.]\n",
+            " [0. 1. 1. 1. 1. 1. 0.]\n",
+            " [0. 1. 1. 1. 1. 1. 0.]\n",
+            " [0. 1. 1. 1. 1. 1. 0.]\n",
+            " [0. 1. 1. 1. 1. 1. 0.]\n",
+            " [0. 1. 1. 1. 1. 1. 0.]\n",
+            " [0. 0. 0. 0. 0. 0. 0.]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 15. What is the result of the following expression?\n",
+        "\n",
+        "(실행 후, 결과에 대한 주석 작성해주세요. ex. 출력 결과에 대한 이유)\n",
+        "\n",
+        "```python\n",
+        "0 * np.nan\n",
+        "np.nan == np.nan\n",
+        "np.inf > np.nan\n",
+        "np.nan - np.nan\n",
+        "np.nan in set([np.nan])\n",
+        "0.3 == 3 * 0.1\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "tggOHEUGM9PK"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "print(0 * np.nan)          # nan: NaN은 계산에 포함되면 결과도 NaN\n",
+        "print(np.nan == np.nan)    # False: NaN은 자기 자신과도 같지 않음\n",
+        "print(np.inf > np.nan)     # False: NaN과 비교하면 False\n",
+        "print(np.nan != np.nan)    # True: NaN은 자기 자신과 같지 않음\n",
+        "print(np.nan in set([np.nan]))  # True: 같은 NaN 객체가 set에 존재함\n",
+        "print(0.3 == 3 * 0.1)      # False: 부동소수점 계산의 정밀도 차이"
+      ],
+      "metadata": {
+        "id": "RmjjLx8_TYNp",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "12ae6da3-a386-47de-ef55-b19d48972427"
+      },
+      "execution_count": 26,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "nan\n",
+            "False\n",
+            "False\n",
+            "True\n",
+            "True\n",
+            "False\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 16. Normalize a 5x5 random matrix.\n",
+        "\n",
+        "(hint: (x - mean) / std)\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[[-1.4765971   0.9582795  -1.29910242  1.0250981  -0.79801651]\n",
+        " [ 0.57945383 -1.28559078  0.02733238  0.99675052  1.2702088 ]\n",
+        " [-0.08513084 -1.4686812  -0.78813593 -0.34559303 -1.15052328]\n",
+        " [ 0.98183813 -1.41255344  0.37190169  1.05697419 -0.02668639]\n",
+        " [-1.14466851  0.98911205  1.14499256  0.69454882  1.18478886]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "28iOVtXXM8gA"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.random.random((5, 5))\n",
+        "a = (a - a.mean()) / a.std()\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "0L0IE4qOTZW4",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "432831f3-d397-4444-bc39-a4f04a5fb4af"
+      },
+      "execution_count": 27,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[-1.99588271 -0.3464484  -0.46320366  1.21216171  1.72254863]\n",
+            " [ 0.9805843   1.38366017 -0.52953676 -1.96591643  0.73929381]\n",
+            " [ 0.47637047  0.5673763  -1.20418587  0.39239036  0.24613627]\n",
+            " [-0.65110178  0.39675138 -1.31227703 -0.5374522   1.20724389]\n",
+            " [ 0.33243034 -0.07954592  0.89048983 -0.2640553  -1.19783139]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 17. Multiply a 5x3 matrix by a 3x2 matrix. (real matrix product)\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[[3. 3.]\n",
+        " [3. 3.]\n",
+        " [3. 3.]\n",
+        " [3. 3.]\n",
+        " [3. 3.]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "asOmp4b5M8dx"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.ones((5, 3)) * 1.1\n",
+        "b = np.ones((3, 2))\n",
+        "print(np.dot(a, b))"
+      ],
+      "metadata": {
+        "id": "01PxOWW5Te7I",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "9139f0a5-bc99-4b42-bd29-24fc57cc6d83"
+      },
+      "execution_count": 28,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[3.3 3.3]\n",
+            " [3.3 3.3]\n",
+            " [3.3 3.3]\n",
+            " [3.3 3.3]\n",
+            " [3.3 3.3]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 18. What are the result of the following expressions?\n",
+        "\n",
+        "(실행 후, 결과에 대한 주석 작성해주세요. ex. 출력 결과에 대한 이유)\n",
+        "\n",
+        "```python\n",
+        "np.array(0) / np.array(0)\n",
+        "np.array(0) // np.array(0)\n",
+        "np.array([np.nan]).astype(int).astype(float)\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "H9zVpsYuM8aR"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "print(np.array(0) / np.array(0))                    # 0을 0으로 나누므로 nan\n",
+        "print(np.array(0) // np.array(0))                   # 0을 0으로 나누는 연산이라 경고가 발생할 수 있음\n",
+        "print(np.array([np.nan]).astype(int).astype(float)) # nan을 정수형으로 변환하면 정수의 최솟값으로 변환될 수 있음"
+      ],
+      "metadata": {
+        "id": "SLP--cFwTh10",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "10c4e9d8-b125-4431-daca-894b6fa26a6f"
+      },
+      "execution_count": 29,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "nan\n",
+            "0\n",
+            "[-9.22337204e+18]\n"
+          ]
+        },
+        {
+          "output_type": "stream",
+          "name": "stderr",
+          "text": [
+            "/tmp/ipykernel_1243/1835376348.py:1: RuntimeWarning: invalid value encountered in divide\n",
+            "  print(np.array(0) / np.array(0))                    # 0을 0으로 나누므로 nan\n",
+            "/tmp/ipykernel_1243/1835376348.py:2: RuntimeWarning: divide by zero encountered in floor_divide\n",
+            "  print(np.array(0) // np.array(0))                   # 0을 0으로 나누는 연산이라 경고가 발생할 수 있음\n",
+            "/tmp/ipykernel_1243/1835376348.py:3: RuntimeWarning: invalid value encountered in cast\n",
+            "  print(np.array([np.nan]).astype(int).astype(float)) # nan을 정수형으로 변환하면 정수의 최솟값으로 변환될 수 있음\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 19. Create a 5x5 matrix with row values ranging from 0 to 4.\n",
+        "\n",
+        "#### ✅ 출력 예시\n",
+        "\n",
+        "```\n",
+        "[[0. 1. 2. 3. 4.]\n",
+        " [0. 1. 2. 3. 4.]\n",
+        " [0. 1. 2. 3. 4.]\n",
+        " [0. 1. 2. 3. 4.]\n",
+        " [0. 1. 2. 3. 4.]]\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "fbi_T8LIO3yc"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.tile(np.arange(5), (5, 1))\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "XHj8J0pLTjrf",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "6bc141bf-bc64-43f7-bab4-bd03b657be87"
+      },
+      "execution_count": 30,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[[0 1 2 3 4]\n",
+            " [0 1 2 3 4]\n",
+            " [0 1 2 3 4]\n",
+            " [0 1 2 3 4]\n",
+            " [0 1 2 3 4]]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 20. Create a random vector of size 10 and sort it.\n",
+        "\n",
+        "#### ✅출력 예시\n",
+        "\n",
+        "\n",
+        "```\n",
+        "[0.11443045 0.16715169 0.32515597 0.38374227 0.48327044 0.78728921\n",
+        " 0.80523192 0.85915686 0.96930939 0.99586525]\n",
+        "\n",
+        "```"
+      ],
+      "metadata": {
+        "id": "cNRIzEzEO_Ft"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "a = np.random.random(10)\n",
+        "a.sort()\n",
+        "print(a)"
+      ],
+      "metadata": {
+        "id": "a3lZxnx-Tngw",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "09e71a85-605f-4383-d641-408424e102d1"
+      },
+      "execution_count": 31,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "[0.16110832 0.16738196 0.18049933 0.31957566 0.39553183 0.44334241\n",
+            " 0.59172898 0.62805866 0.89075051 0.9702591 ]\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "## **판다스**"
+      ],
+      "metadata": {
+        "id": "fkX-tY1oKDq5"
+      }
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "yl7zlBgszyCS"
+      },
+      "source": [
+        "\n",
+        "### 1. Import pandas under the alias `pd`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "import pandas as pd"
+      ],
+      "metadata": {
+        "id": "ZiANPeHhz00W"
+      },
+      "execution_count": 32,
+      "outputs": []
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "2Hk3SuquzyCU"
+      },
+      "source": [
+        "### 2. Print the version of pandas that has been imported."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "print(pd.__version__)"
+      ],
+      "metadata": {
+        "id": "i2NtsBbjz1x2",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "7c41e384-67aa-450b-e4c7-cf5e0a498cd4"
+      },
+      "execution_count": 33,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "2.2.3\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "oOTRFQtFzyCV"
+      },
+      "source": [
+        "## 3~20번 문제는 아래 데이터프레임으로 진행됩니다.\n",
+        "\n",
+        "Consider the following Python dictionary `data` and Python list `labels`:\n",
+        "\n",
+        "``` python\n",
+        "data = {'animal': ['cat', 'cat', 'snake', 'dog', 'dog', 'cat', 'snake', 'cat', 'dog', 'dog'],\n",
+        "        'age': [2.5, 3, 0.5, np.nan, 5, 2, 4.5, np.nan, 7, 3],\n",
+        "        'visits': [1, 3, 2, 3, 2, 3, 1, 1, 2, 1],\n",
+        "        'priority': ['yes', 'yes', 'no', 'yes', 'no', 'no', 'no', 'yes', 'no', 'no']}\n",
+        "\n",
+        "labels = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']\n",
+        "```\n"
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 3. Create a DataFrame `df` from this dictionary `data` which has the index `labels`.\n"
+      ],
+      "metadata": {
+        "id": "m_8US0jJzyCW"
+      }
+    },
+    {
+      "cell_type": "code",
+      "execution_count": 34,
+      "metadata": {
+        "id": "7CbS_gtmzyCW",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 363
+        },
+        "outputId": "bb220722-aa5c-4ccb-8e9b-449d9ecd8980"
+      },
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "a    cat  2.5       1      yes\n",
+              "b    cat  3.0       3      yes\n",
+              "c  snake  0.5       2       no\n",
+              "d    dog  NaN       3      yes\n",
+              "e    dog  5.0       2       no\n",
+              "f    cat  2.0       3       no\n",
+              "g  snake  4.5       1       no\n",
+              "h    cat  NaN       1      yes\n",
+              "i    dog  7.0       2       no\n",
+              "j    dog  3.0       1       no"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-524ca155-bdfa-46f3-8e94-bff53bbb025a\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>0.5</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>g</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>4.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>1</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-524ca155-bdfa-46f3-8e94-bff53bbb025a')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-524ca155-bdfa-46f3-8e94-bff53bbb025a button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-524ca155-bdfa-46f3-8e94-bff53bbb025a');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "  <div id=\"id_2f1fd359-4db2-480e-8f0d-025bd0093497\">\n",
+              "    <style>\n",
+              "      .colab-df-generate {\n",
+              "        background-color: #E8F0FE;\n",
+              "        border: none;\n",
+              "        border-radius: 50%;\n",
+              "        cursor: pointer;\n",
+              "        display: none;\n",
+              "        fill: #1967D2;\n",
+              "        height: 32px;\n",
+              "        padding: 0 0 0 0;\n",
+              "        width: 32px;\n",
+              "      }\n",
+              "\n",
+              "      .colab-df-generate:hover {\n",
+              "        background-color: #E2EBFA;\n",
+              "        box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "        fill: #174EA6;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate {\n",
+              "        background-color: #3B4455;\n",
+              "        fill: #D2E3FC;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate:hover {\n",
+              "        background-color: #434B5C;\n",
+              "        box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "        filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "        fill: #FFFFFF;\n",
+              "      }\n",
+              "    </style>\n",
+              "    <button class=\"colab-df-generate\" onclick=\"generateWithVariable('df')\"\n",
+              "            title=\"Generate code using this dataframe.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\"viewBox=\"0 0 24 24\"\n",
+              "       width=\"24px\">\n",
+              "    <path d=\"M7,19H8.4L18.45,9,17,7.55,7,17.6ZM5,21V16.75L18.45,3.32a2,2,0,0,1,2.83,0l1.4,1.43a1.91,1.91,0,0,1,.58,1.4,1.91,1.91,0,0,1-.58,1.4L9.25,21ZM18.45,9,17,7.55Zm-12,3A5.31,5.31,0,0,0,4.9,8.1,5.31,5.31,0,0,0,1,6.5,5.31,5.31,0,0,0,4.9,4.9,5.31,5.31,0,0,0,6.5,1,5.31,5.31,0,0,0,8.1,4.9,5.31,5.31,0,0,0,12,6.5,5.46,5.46,0,0,0,6.5,12Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "    <script>\n",
+              "      (() => {\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#id_2f1fd359-4db2-480e-8f0d-025bd0093497 button.colab-df-generate');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      buttonEl.onclick = () => {\n",
+              "        google.colab.notebook.generateWithVariable('df');\n",
+              "      }\n",
+              "      })();\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "variable_name": "df",
+              "summary": "{\n  \"name\": \"df\",\n  \"rows\": 10,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 3,\n        \"samples\": [\n          \"cat\",\n          \"snake\",\n          \"dog\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 2.0077973005261263,\n        \"min\": 0.5,\n        \"max\": 7.0,\n        \"num_unique_values\": 7,\n        \"samples\": [\n          2.5,\n          3.0,\n          4.5\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0,\n        \"min\": 1,\n        \"max\": 3,\n        \"num_unique_values\": 3,\n        \"samples\": [\n          1,\n          3,\n          2\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"priority\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"no\",\n          \"yes\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 34
+        }
+      ],
+      "source": [
+        "import numpy as np\n",
+        "\n",
+        "data = {'animal': ['cat', 'cat', 'snake', 'dog', 'dog', 'cat', 'snake', 'cat', 'dog', 'dog'],\n",
+        "        'age': [2.5, 3, 0.5, np.nan, 5, 2, 4.5, np.nan, 7, 3],\n",
+        "        'visits': [1, 3, 2, 3, 2, 3, 1, 1, 2, 1],\n",
+        "        'priority': ['yes', 'yes', 'no', 'yes', 'no', 'no', 'no', 'yes', 'no', 'no']}\n",
+        "\n",
+        "labels = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']\n",
+        "\n",
+        "df = pd.DataFrame(data, index=labels)\n",
+        "df"
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "f2shsFGyzyCW"
+      },
+      "source": [
+        "### 4. Display a summary of the basic information about this DataFrame and its data.  \n",
+        "(hint: there is a single method that can be called on the DataFrame)"
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.info()"
+      ],
+      "metadata": {
+        "id": "BWZpEuGtz7ky",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "9303114f-34b0-4749-ba4e-fc7151a29a8f"
+      },
+      "execution_count": 35,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "<class 'pandas.core.frame.DataFrame'>\n",
+            "Index: 10 entries, a to j\n",
+            "Data columns (total 4 columns):\n",
+            " #   Column    Non-Null Count  Dtype  \n",
+            "---  ------    --------------  -----  \n",
+            " 0   animal    10 non-null     object \n",
+            " 1   age       8 non-null      float64\n",
+            " 2   visits    10 non-null     int64  \n",
+            " 3   priority  10 non-null     object \n",
+            "dtypes: float64(1), int64(1), object(2)\n",
+            "memory usage: 700.0+ bytes\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        "### 5. Display a summary of the basic statistics about data of this DataFrame.  \n",
+        "(hint: there is a single method that can be called on the DataFrame)"
+      ],
+      "metadata": {
+        "id": "AfbkaEOyzyCX"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.describe()"
+      ],
+      "metadata": {
+        "id": "wzzc100Oz8c3",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 300
+        },
+        "outputId": "c61da426-c748-4209-e213-8cd9808103f7"
+      },
+      "execution_count": 36,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "            age     visits\n",
+              "count  8.000000  10.000000\n",
+              "mean   3.437500   1.900000\n",
+              "std    2.007797   0.875595\n",
+              "min    0.500000   1.000000\n",
+              "25%    2.375000   1.000000\n",
+              "50%    3.000000   2.000000\n",
+              "75%    4.625000   2.750000\n",
+              "max    7.000000   3.000000"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-b12102a9-d5a1-4424-b6ef-800bae80f28c\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>count</th>\n",
+              "      <td>8.000000</td>\n",
+              "      <td>10.000000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>mean</th>\n",
+              "      <td>3.437500</td>\n",
+              "      <td>1.900000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>std</th>\n",
+              "      <td>2.007797</td>\n",
+              "      <td>0.875595</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>min</th>\n",
+              "      <td>0.500000</td>\n",
+              "      <td>1.000000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>25%</th>\n",
+              "      <td>2.375000</td>\n",
+              "      <td>1.000000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>50%</th>\n",
+              "      <td>3.000000</td>\n",
+              "      <td>2.000000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>75%</th>\n",
+              "      <td>4.625000</td>\n",
+              "      <td>2.750000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>max</th>\n",
+              "      <td>7.000000</td>\n",
+              "      <td>3.000000</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-b12102a9-d5a1-4424-b6ef-800bae80f28c')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-b12102a9-d5a1-4424-b6ef-800bae80f28c button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-b12102a9-d5a1-4424-b6ef-800bae80f28c');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df\",\n  \"rows\": 8,\n  \"fields\": [\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 2.5474771307751376,\n        \"min\": 0.5,\n        \"max\": 8.0,\n        \"num_unique_values\": 8,\n        \"samples\": [\n          3.4375,\n          3.0,\n          8.0\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 3.0122099789789663,\n        \"min\": 0.8755950357709131,\n        \"max\": 10.0,\n        \"num_unique_values\": 7,\n        \"samples\": [\n          10.0,\n          1.9,\n          2.75\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 36
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "XJ59aPcrzyCX"
+      },
+      "source": [
+        "### 6. Return the first 3 rows of the DataFrame `df`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.head(3)"
+      ],
+      "metadata": {
+        "id": "vZro7sh9z_rY",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 143
+        },
+        "outputId": "6b1cbcb5-b659-4e0f-9b3b-61a5d7419b7d"
+      },
+      "execution_count": 37,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "a    cat  2.5       1      yes\n",
+              "b    cat  3.0       3      yes\n",
+              "c  snake  0.5       2       no"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-1b7f646d-6447-4a9f-b1c6-de82db87f8c7\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>0.5</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-1b7f646d-6447-4a9f-b1c6-de82db87f8c7')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
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+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-1b7f646d-6447-4a9f-b1c6-de82db87f8c7 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-1b7f646d-6447-4a9f-b1c6-de82db87f8c7');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "variable_name": "df",
+              "summary": "{\n  \"name\": \"df\",\n  \"rows\": 10,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 3,\n        \"samples\": [\n          \"cat\",\n          \"snake\",\n          \"dog\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 2.0077973005261263,\n        \"min\": 0.5,\n        \"max\": 7.0,\n        \"num_unique_values\": 7,\n        \"samples\": [\n          2.5,\n          3.0,\n          4.5\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0,\n        \"min\": 1,\n        \"max\": 3,\n        \"num_unique_values\": 3,\n        \"samples\": [\n          1,\n          3,\n          2\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"priority\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"no\",\n          \"yes\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 37
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "KBVp0_3ZzyCY"
+      },
+      "source": [
+        "### 7. Select just the 'animal' and 'age' columns from the DataFrame `df`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df[['animal', 'age']]"
+      ],
+      "metadata": {
+        "id": "pC6sH-1F0AJo",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 363
+        },
+        "outputId": "fc5b0714-1330-4bf7-fab4-143dd6d81222"
+      },
+      "execution_count": 38,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age\n",
+              "a    cat  2.5\n",
+              "b    cat  3.0\n",
+              "c  snake  0.5\n",
+              "d    dog  NaN\n",
+              "e    dog  5.0\n",
+              "f    cat  2.0\n",
+              "g  snake  4.5\n",
+              "h    cat  NaN\n",
+              "i    dog  7.0\n",
+              "j    dog  3.0"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-84b67286-ebef-4689-8d2a-0ac107257299\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>0.5</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.0</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>g</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>4.5</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-84b67286-ebef-4689-8d2a-0ac107257299')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
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+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-84b67286-ebef-4689-8d2a-0ac107257299 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-84b67286-ebef-4689-8d2a-0ac107257299');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df[['animal', 'age']]\",\n  \"rows\": 10,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 3,\n        \"samples\": [\n          \"cat\",\n          \"snake\",\n          \"dog\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 2.0077973005261263,\n        \"min\": 0.5,\n        \"max\": 7.0,\n        \"num_unique_values\": 7,\n        \"samples\": [\n          2.5,\n          3.0,\n          4.5\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 38
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "a1giftRYzyCY"
+      },
+      "source": [
+        "### 8. Select the data in rows `[3, 4, 8]` **and** in columns `['animal', 'age']`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.iloc[[3, 4, 8]][['animal', 'age']]"
+      ],
+      "metadata": {
+        "id": "tkSynFGH0BLD",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 143
+        },
+        "outputId": "9e021f9b-30dd-48dc-d184-2fc06c4550c7"
+      },
+      "execution_count": 39,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age\n",
+              "d    dog  NaN\n",
+              "e    dog  5.0\n",
+              "i    dog  7.0"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-b0866ba5-1b34-4331-90a2-bbd60d033509\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-b0866ba5-1b34-4331-90a2-bbd60d033509')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-b0866ba5-1b34-4331-90a2-bbd60d033509 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-b0866ba5-1b34-4331-90a2-bbd60d033509');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df\",\n  \"rows\": 3,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 1,\n        \"samples\": [\n          \"dog\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 1.4142135623730951,\n        \"min\": 5.0,\n        \"max\": 7.0,\n        \"num_unique_values\": 2,\n        \"samples\": [\n          7.0\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 39
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "67sYTLBqzyCY"
+      },
+      "source": [
+        "### 9. Select only the rows where the number of visits is greater than 3."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df[df['visits'] > 3]"
+      ],
+      "metadata": {
+        "id": "d_G0WeMG0Dgd",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 53
+        },
+        "outputId": "4bccaf6c-6854-42d1-b575-7ab440073a99"
+      },
+      "execution_count": 40,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "Empty DataFrame\n",
+              "Columns: [animal, age, visits, priority]\n",
+              "Index: []"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-5afa97f5-881f-4a10-afb6-2ca482c061fa\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-5afa97f5-881f-4a10-afb6-2ca482c061fa')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-5afa97f5-881f-4a10-afb6-2ca482c061fa button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-5afa97f5-881f-4a10-afb6-2ca482c061fa');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "repr_error": "Out of range float values are not JSON compliant: nan"
+            }
+          },
+          "metadata": {},
+          "execution_count": 40
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "FXX4YRWgzyCY"
+      },
+      "source": [
+        "### 10. Select the rows where the age is missing, i.e. it is `NaN`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df[df['age'].isnull()]"
+      ],
+      "metadata": {
+        "id": "KaV4Ypkj0Ea2",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 112
+        },
+        "outputId": "01b989bc-65e0-4971-f75a-fa96e86d2038"
+      },
+      "execution_count": 41,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "d    dog  NaN       3      yes\n",
+              "h    cat  NaN       1      yes"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-00e66590-4809-4d1c-b9c5-d09493eb9df1\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-00e66590-4809-4d1c-b9c5-d09493eb9df1')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-00e66590-4809-4d1c-b9c5-d09493eb9df1 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-00e66590-4809-4d1c-b9c5-d09493eb9df1');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df[df['age']\",\n  \"rows\": 2,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"string\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"cat\",\n          \"dog\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": null,\n        \"min\": null,\n        \"max\": null,\n        \"num_unique_values\": 0,\n        \"samples\": [],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 1,\n        \"min\": 1,\n        \"max\": 3,\n        \"num_unique_values\": 2,\n        \"samples\": [],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"priority\",\n      \"properties\": {\n        \"dtype\": \"string\",\n        \"num_unique_values\": 1,\n        \"samples\": [],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 41
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "kMH5n-UBzyCZ"
+      },
+      "source": [
+        "### 11. Select the rows where the animal is a cat *and* the age is less than 3."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df[(df['animal'] == 'cat') & (df['age'] < 3)]"
+      ],
+      "metadata": {
+        "id": "8sCDh9Ez0FND",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 112
+        },
+        "outputId": "aa616225-d14a-45ae-f2a4-6682ab5ae8ba"
+      },
+      "execution_count": 42,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "a    cat  2.5       1      yes\n",
+              "f    cat  2.0       3       no"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-4fa85a78-72a9-42a6-bd65-2869c7371c94\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-4fa85a78-72a9-42a6-bd65-2869c7371c94')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-4fa85a78-72a9-42a6-bd65-2869c7371c94 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-4fa85a78-72a9-42a6-bd65-2869c7371c94');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df[(df['animal'] == 'cat') & (df['age'] < 3)]\",\n  \"rows\": 2,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"string\",\n        \"num_unique_values\": 1,\n        \"samples\": [\n          \"cat\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0.3535533905932738,\n        \"min\": 2.0,\n        \"max\": 2.5,\n        \"num_unique_values\": 2,\n        \"samples\": [\n          2.0\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 1,\n        \"min\": 1,\n        \"max\": 3,\n        \"num_unique_values\": 2,\n        \"samples\": [\n          3\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"priority\",\n      \"properties\": {\n        \"dtype\": \"string\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"no\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 42
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "62Y0JsYazyCZ"
+      },
+      "source": [
+        "### 12. Select the rows the age is between 2 and 4 (inclusive).  \n"
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df[df['age'].between(2, 4)]"
+      ],
+      "metadata": {
+        "id": "svjvRtgZ0G76",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 175
+        },
+        "outputId": "343b09f1-89ea-4ed8-bfab-e6e923d968ce"
+      },
+      "execution_count": 43,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "a    cat  2.5       1      yes\n",
+              "b    cat  3.0       3      yes\n",
+              "f    cat  2.0       3       no\n",
+              "j    dog  3.0       1       no"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-9adad496-b96a-4a94-aad0-8ec78ceb9873\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>1</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-9adad496-b96a-4a94-aad0-8ec78ceb9873')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
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+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-9adad496-b96a-4a94-aad0-8ec78ceb9873 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-9adad496-b96a-4a94-aad0-8ec78ceb9873');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df[df['age']\",\n  \"rows\": 4,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"string\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"dog\",\n          \"cat\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0.47871355387816905,\n        \"min\": 2.0,\n        \"max\": 3.0,\n        \"num_unique_values\": 3,\n        \"samples\": [\n          2.5,\n          3.0\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 1,\n        \"min\": 1,\n        \"max\": 3,\n        \"num_unique_values\": 2,\n        \"samples\": [\n          3,\n          1\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"priority\",\n      \"properties\": {\n        \"dtype\": \"string\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"no\",\n          \"yes\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 43
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "4lIGMIkPzyCZ"
+      },
+      "source": [
+        "### 13. Change the age in row 'f' to 1.5."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.loc['f', 'age'] = 1.5\n",
+        "df"
+      ],
+      "metadata": {
+        "id": "h4U4A6Ai0Hvk",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 363
+        },
+        "outputId": "9609be1c-f56e-49dc-fbf4-3c74c53a0507"
+      },
+      "execution_count": 60,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "a    cat  2.5       1      NaN\n",
+              "b    cat  3.0       3      NaN\n",
+              "c  snake  0.5       2      NaN\n",
+              "d    dog  NaN       3      NaN\n",
+              "e    dog  5.0       2      NaN\n",
+              "f    cat  1.5       3      NaN\n",
+              "g  snake  4.5       1      NaN\n",
+              "h    cat  NaN       1      NaN\n",
+              "i    dog  7.0       2      NaN\n",
+              "j    dog  3.0       1      NaN"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-05d9b2a5-6940-4313-bcc0-6b67129210e9\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>0.5</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>1.5</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>g</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>4.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-05d9b2a5-6940-4313-bcc0-6b67129210e9')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
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+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
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+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-05d9b2a5-6940-4313-bcc0-6b67129210e9 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-05d9b2a5-6940-4313-bcc0-6b67129210e9');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "  <div id=\"id_4ae0b3bb-f61b-426d-862c-576e78013e5c\">\n",
+              "    <style>\n",
+              "      .colab-df-generate {\n",
+              "        background-color: #E8F0FE;\n",
+              "        border: none;\n",
+              "        border-radius: 50%;\n",
+              "        cursor: pointer;\n",
+              "        display: none;\n",
+              "        fill: #1967D2;\n",
+              "        height: 32px;\n",
+              "        padding: 0 0 0 0;\n",
+              "        width: 32px;\n",
+              "      }\n",
+              "\n",
+              "      .colab-df-generate:hover {\n",
+              "        background-color: #E2EBFA;\n",
+              "        box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "        fill: #174EA6;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate {\n",
+              "        background-color: #3B4455;\n",
+              "        fill: #D2E3FC;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate:hover {\n",
+              "        background-color: #434B5C;\n",
+              "        box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "        filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "        fill: #FFFFFF;\n",
+              "      }\n",
+              "    </style>\n",
+              "    <button class=\"colab-df-generate\" onclick=\"generateWithVariable('df')\"\n",
+              "            title=\"Generate code using this dataframe.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\"viewBox=\"0 0 24 24\"\n",
+              "       width=\"24px\">\n",
+              "    <path d=\"M7,19H8.4L18.45,9,17,7.55,7,17.6ZM5,21V16.75L18.45,3.32a2,2,0,0,1,2.83,0l1.4,1.43a1.91,1.91,0,0,1,.58,1.4,1.91,1.91,0,0,1-.58,1.4L9.25,21ZM18.45,9,17,7.55Zm-12,3A5.31,5.31,0,0,0,4.9,8.1,5.31,5.31,0,0,0,1,6.5,5.31,5.31,0,0,0,4.9,4.9,5.31,5.31,0,0,0,6.5,1,5.31,5.31,0,0,0,8.1,4.9,5.31,5.31,0,0,0,12,6.5,5.46,5.46,0,0,0,6.5,12Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "    <script>\n",
+              "      (() => {\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#id_4ae0b3bb-f61b-426d-862c-576e78013e5c button.colab-df-generate');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      buttonEl.onclick = () => {\n",
+              "        google.colab.notebook.generateWithVariable('df');\n",
+              "      }\n",
+              "      })();\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "variable_name": "df",
+              "repr_error": "Out of range float values are not JSON compliant: nan"
+            }
+          },
+          "metadata": {},
+          "execution_count": 60
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "FZzPr9ObzyCZ"
+      },
+      "source": [
+        "### 14. Calculate the sum of all visits in `df` (i.e. the total number of visits)."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df['visits'].sum()"
+      ],
+      "metadata": {
+        "id": "FXLAUqR40I6C",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "ab6b99b3-80e8-49ab-f63b-e98a2ca2936b"
+      },
+      "execution_count": 48,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "np.int64(19)"
+            ]
+          },
+          "metadata": {},
+          "execution_count": 48
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "PO0xpJ_OzyCa"
+      },
+      "source": [
+        "### 15. Calculate the mean age for each different animal in `df`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.groupby('animal')['age'].mean()"
+      ],
+      "metadata": {
+        "id": "L63WRx_20Kta",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 210
+        },
+        "outputId": "38b653e8-5150-484d-c351-b1a1eed9ff00"
+      },
+      "execution_count": 49,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "animal\n",
+              "cat      2.333333\n",
+              "dog      5.000000\n",
+              "snake    2.500000\n",
+              "Name: age, dtype: float64"
+            ],
+            "text/html": [
+              "<div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>age</th>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>animal</th>\n",
+              "      <th></th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>cat</th>\n",
+              "      <td>2.333333</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>dog</th>\n",
+              "      <td>5.000000</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>snake</th>\n",
+              "      <td>2.500000</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div><br><label><b>dtype:</b> float64</label>"
+            ]
+          },
+          "metadata": {},
+          "execution_count": 49
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "YfVdzQXIzyCa"
+      },
+      "source": [
+        "### 16. Append a new row 'k' to `df` with your choice of values for each column. Then delete that row to return the original DataFrame."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.loc['k'] = ['dog', 5.5, 2, 'no']\n",
+        "print(\"추가된 후 df의 마지막 부분:\\n\", df.tail(3))\n",
+        "\n",
+        "df = df.drop('k')\n",
+        "print(\"\\n삭제된 후 df의 마지막 부분:\\n\", df.tail(3))"
+      ],
+      "metadata": {
+        "id": "Per12Ekp0Mc0",
+        "colab": {
+          "base_uri": "https://localhost:8080/"
+        },
+        "outputId": "6580a011-b0fe-401c-eee3-0743e8c7d33d"
+      },
+      "execution_count": 59,
+      "outputs": [
+        {
+          "output_type": "stream",
+          "name": "stdout",
+          "text": [
+            "추가된 후 df의 마지막 부분:\n",
+            "   animal  age  visits priority\n",
+            "i    dog  7.0       2      NaN\n",
+            "j    dog  3.0       1      NaN\n",
+            "k    dog  5.5       2       no\n",
+            "\n",
+            "삭제된 후 df의 마지막 부분:\n",
+            "   animal  age  visits priority\n",
+            "h    cat  NaN       1      NaN\n",
+            "i    dog  7.0       2      NaN\n",
+            "j    dog  3.0       1      NaN\n"
+          ]
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "tDkk_tHszyCa"
+      },
+      "source": [
+        "### 17. Count the number of each type of animal in `df`."
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df['animal'].value_counts()"
+      ],
+      "metadata": {
+        "id": "v21izXST0NTR",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 210
+        },
+        "outputId": "9bb68117-05e1-4553-f00d-a718e7e626dd"
+      },
+      "execution_count": 51,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "animal\n",
+              "cat      4\n",
+              "dog      4\n",
+              "snake    2\n",
+              "Name: count, dtype: int64"
+            ],
+            "text/html": [
+              "<div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>count</th>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>animal</th>\n",
+              "      <th></th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>cat</th>\n",
+              "      <td>4</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>dog</th>\n",
+              "      <td>4</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>snake</th>\n",
+              "      <td>2</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div><br><label><b>dtype:</b> int64</label>"
+            ]
+          },
+          "metadata": {},
+          "execution_count": 51
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "cwz4s5RYzyCa"
+      },
+      "source": [
+        "### 18. Sort `df` first by the values in the 'age' in *decending* order, then by the value in the 'visits' column in *ascending* order (so row `i` should be first, and row `d` should be last).\n",
+        "#### ✅출력 예시"
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "source": [
+        " index |animal\t| age\t|visits|\tpriority\n",
+        "---|---|---|---|---\n",
+        "i|\tdog|\t7.0|\t2|\tno\n",
+        "e|\tdog|\t5.0|\t2|\tno\n",
+        "g|\tsnake|\t4.5|\t1|\tno\n",
+        "j|\tdog|\t3.0|\t1|\tno\n",
+        "b|\tcat|\t3.0|\t3|\tyes\n",
+        "a|\tcat|\t2.5|\t1|\tyes\n",
+        "f|\tcat|\t1.5|\t3|\tno\n",
+        "c|\tsnake|\t0.5|\t2|\tno\n",
+        "h|\tcat|\tNaN|\t1|\tyes\n",
+        "d|\tdog|\tNaN|\t3|\tyes"
+      ],
+      "metadata": {
+        "id": "YILpLKeqzyCa"
+      }
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df.sort_values(by=['age', 'visits'], ascending=[False, True])"
+      ],
+      "metadata": {
+        "id": "2l6Pb7T10Qpi",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 363
+        },
+        "outputId": "f58f44fc-c54f-4fb3-9b71-f91a232fd490"
+      },
+      "execution_count": 52,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "i    dog  7.0       2       no\n",
+              "e    dog  5.0       2       no\n",
+              "g  snake  4.5       1       no\n",
+              "j    dog  3.0       1       no\n",
+              "b    cat  3.0       3      yes\n",
+              "a    cat  2.5       1      yes\n",
+              "f    cat  1.5       3       no\n",
+              "c  snake  0.5       2       no\n",
+              "h    cat  NaN       1      yes\n",
+              "d    dog  NaN       3      yes"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-cf57f688-3be6-4591-8168-85e12f995364\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>g</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>4.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>1</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>1.5</td>\n",
+              "      <td>3</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>0.5</td>\n",
+              "      <td>2</td>\n",
+              "      <td>no</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>1</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>3</td>\n",
+              "      <td>yes</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-cf57f688-3be6-4591-8168-85e12f995364')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-cf57f688-3be6-4591-8168-85e12f995364 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-cf57f688-3be6-4591-8168-85e12f995364');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "summary": "{\n  \"name\": \"df\",\n  \"rows\": 10,\n  \"fields\": [\n    {\n      \"column\": \"animal\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 3,\n        \"samples\": [\n          \"dog\",\n          \"snake\",\n          \"cat\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"age\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 2.065879266282796,\n        \"min\": 0.5,\n        \"max\": 7.0,\n        \"num_unique_values\": 7,\n        \"samples\": [\n          7.0,\n          5.0,\n          1.5\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"visits\",\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0,\n        \"min\": 1,\n        \"max\": 3,\n        \"num_unique_values\": 3,\n        \"samples\": [\n          2,\n          1,\n          3\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": \"priority\",\n      \"properties\": {\n        \"dtype\": \"category\",\n        \"num_unique_values\": 2,\n        \"samples\": [\n          \"yes\",\n          \"no\"\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 52
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "6hfE99qHzyCb"
+      },
+      "source": [
+        "### 19. The 'priority' column contains the values 'yes' and 'no'. Replace this column with a column of boolean values: 'yes' should be `True` and 'no' should be `False`.  \n",
+        "(hint: `map`)"
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df['priority'] = df['priority'].map({'yes': True, 'no': False})\n",
+        "df"
+      ],
+      "metadata": {
+        "id": "lPLmBRUP0SnR",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 363
+        },
+        "outputId": "22278948-5df9-48f5-822e-3b798915ef7a"
+      },
+      "execution_count": 58,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "  animal  age  visits priority\n",
+              "a    cat  2.5       1      NaN\n",
+              "b    cat  3.0       3      NaN\n",
+              "c  snake  0.5       2      NaN\n",
+              "d    dog  NaN       3      NaN\n",
+              "e    dog  5.0       2      NaN\n",
+              "f    cat  1.5       3      NaN\n",
+              "g  snake  4.5       1      NaN\n",
+              "h    cat  NaN       1      NaN\n",
+              "i    dog  7.0       2      NaN\n",
+              "j    dog  3.0       1      NaN"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-f059f575-6cb5-479f-8618-e286231d7f8f\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
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+              "        vertical-align: top;\n",
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+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
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+              "      <th>a</th>\n",
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+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
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+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>0.5</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
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+              "      <td>dog</td>\n",
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+              "      <td>3</td>\n",
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+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
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+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>1.5</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
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+              "      <th>g</th>\n",
+              "      <td>snake</td>\n",
+              "      <td>4.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
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+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
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+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
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+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
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+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
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+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
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+              "  </svg>\n",
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+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
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+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
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+              "      width: 32px;\n",
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+              "\n",
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+              "      fill: #174EA6;\n",
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+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-f059f575-6cb5-479f-8618-e286231d7f8f button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-f059f575-6cb5-479f-8618-e286231d7f8f');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "  <div id=\"id_c4552afe-0e30-41cb-907f-d5ef803b608a\">\n",
+              "    <style>\n",
+              "      .colab-df-generate {\n",
+              "        background-color: #E8F0FE;\n",
+              "        border: none;\n",
+              "        border-radius: 50%;\n",
+              "        cursor: pointer;\n",
+              "        display: none;\n",
+              "        fill: #1967D2;\n",
+              "        height: 32px;\n",
+              "        padding: 0 0 0 0;\n",
+              "        width: 32px;\n",
+              "      }\n",
+              "\n",
+              "      .colab-df-generate:hover {\n",
+              "        background-color: #E2EBFA;\n",
+              "        box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "        fill: #174EA6;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate {\n",
+              "        background-color: #3B4455;\n",
+              "        fill: #D2E3FC;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate:hover {\n",
+              "        background-color: #434B5C;\n",
+              "        box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "        filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "        fill: #FFFFFF;\n",
+              "      }\n",
+              "    </style>\n",
+              "    <button class=\"colab-df-generate\" onclick=\"generateWithVariable('df')\"\n",
+              "            title=\"Generate code using this dataframe.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\"viewBox=\"0 0 24 24\"\n",
+              "       width=\"24px\">\n",
+              "    <path d=\"M7,19H8.4L18.45,9,17,7.55,7,17.6ZM5,21V16.75L18.45,3.32a2,2,0,0,1,2.83,0l1.4,1.43a1.91,1.91,0,0,1,.58,1.4,1.91,1.91,0,0,1-.58,1.4L9.25,21ZM18.45,9,17,7.55Zm-12,3A5.31,5.31,0,0,0,4.9,8.1,5.31,5.31,0,0,0,1,6.5,5.31,5.31,0,0,0,4.9,4.9,5.31,5.31,0,0,0,6.5,1,5.31,5.31,0,0,0,8.1,4.9,5.31,5.31,0,0,0,12,6.5,5.46,5.46,0,0,0,6.5,12Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "    <script>\n",
+              "      (() => {\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#id_c4552afe-0e30-41cb-907f-d5ef803b608a button.colab-df-generate');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      buttonEl.onclick = () => {\n",
+              "        google.colab.notebook.generateWithVariable('df');\n",
+              "      }\n",
+              "      })();\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "variable_name": "df",
+              "repr_error": "Out of range float values are not JSON compliant: nan"
+            }
+          },
+          "metadata": {},
+          "execution_count": 58
+        }
+      ]
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "ycaIJncEzyCb"
+      },
+      "source": [
+        "### 20. In the 'animal' column, change the 'snake' entries to 'python'.   "
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "df['animal'] = df['animal'].replace('snake', 'python')\n",
+        "df"
+      ],
+      "metadata": {
+        "id": "MZelDUlE0Wag",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 363
+        },
+        "outputId": "df356c40-4230-4549-8438-a5e549e71094"
+      },
+      "execution_count": 61,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "   animal  age  visits priority\n",
+              "a     cat  2.5       1      NaN\n",
+              "b     cat  3.0       3      NaN\n",
+              "c  python  0.5       2      NaN\n",
+              "d     dog  NaN       3      NaN\n",
+              "e     dog  5.0       2      NaN\n",
+              "f     cat  1.5       3      NaN\n",
+              "g  python  4.5       1      NaN\n",
+              "h     cat  NaN       1      NaN\n",
+              "i     dog  7.0       2      NaN\n",
+              "j     dog  3.0       1      NaN"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-bf84c765-701a-4188-9aaa-96149fc59e46\" class=\"colab-df-container\">\n",
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+              "    .dataframe tbody tr th:only-of-type {\n",
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+              "\n",
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+              "        vertical-align: top;\n",
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+              "\n",
+              "    .dataframe thead th {\n",
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+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>animal</th>\n",
+              "      <th>age</th>\n",
+              "      <th>visits</th>\n",
+              "      <th>priority</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>a</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>2.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
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+              "    <tr>\n",
+              "      <th>b</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>c</th>\n",
+              "      <td>python</td>\n",
+              "      <td>0.5</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>d</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>e</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>5.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>f</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>1.5</td>\n",
+              "      <td>3</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>g</th>\n",
+              "      <td>python</td>\n",
+              "      <td>4.5</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>h</th>\n",
+              "      <td>cat</td>\n",
+              "      <td>NaN</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>i</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>7.0</td>\n",
+              "      <td>2</td>\n",
+              "      <td>NaN</td>\n",
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+              "    <tr>\n",
+              "      <th>j</th>\n",
+              "      <td>dog</td>\n",
+              "      <td>3.0</td>\n",
+              "      <td>1</td>\n",
+              "      <td>NaN</td>\n",
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+              "            style=\"display:none;\">\n",
+              "\n",
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+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
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+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
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+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-bf84c765-701a-4188-9aaa-96149fc59e46 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-bf84c765-701a-4188-9aaa-96149fc59e46');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "  <div id=\"id_04163ea8-1ce6-4b72-b557-b701284351d1\">\n",
+              "    <style>\n",
+              "      .colab-df-generate {\n",
+              "        background-color: #E8F0FE;\n",
+              "        border: none;\n",
+              "        border-radius: 50%;\n",
+              "        cursor: pointer;\n",
+              "        display: none;\n",
+              "        fill: #1967D2;\n",
+              "        height: 32px;\n",
+              "        padding: 0 0 0 0;\n",
+              "        width: 32px;\n",
+              "      }\n",
+              "\n",
+              "      .colab-df-generate:hover {\n",
+              "        background-color: #E2EBFA;\n",
+              "        box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "        fill: #174EA6;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate {\n",
+              "        background-color: #3B4455;\n",
+              "        fill: #D2E3FC;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate:hover {\n",
+              "        background-color: #434B5C;\n",
+              "        box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "        filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "        fill: #FFFFFF;\n",
+              "      }\n",
+              "    </style>\n",
+              "    <button class=\"colab-df-generate\" onclick=\"generateWithVariable('df')\"\n",
+              "            title=\"Generate code using this dataframe.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\"viewBox=\"0 0 24 24\"\n",
+              "       width=\"24px\">\n",
+              "    <path d=\"M7,19H8.4L18.45,9,17,7.55,7,17.6ZM5,21V16.75L18.45,3.32a2,2,0,0,1,2.83,0l1.4,1.43a1.91,1.91,0,0,1,.58,1.4,1.91,1.91,0,0,1-.58,1.4L9.25,21ZM18.45,9,17,7.55Zm-12,3A5.31,5.31,0,0,0,4.9,8.1,5.31,5.31,0,0,0,1,6.5,5.31,5.31,0,0,0,4.9,4.9,5.31,5.31,0,0,0,6.5,1,5.31,5.31,0,0,0,8.1,4.9,5.31,5.31,0,0,0,12,6.5,5.46,5.46,0,0,0,6.5,12Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "    <script>\n",
+              "      (() => {\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#id_04163ea8-1ce6-4b72-b557-b701284351d1 button.colab-df-generate');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      buttonEl.onclick = () => {\n",
+              "        google.colab.notebook.generateWithVariable('df');\n",
+              "      }\n",
+              "      })();\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "variable_name": "df",
+              "repr_error": "Out of range float values are not JSON compliant: nan"
+            }
+          },
+          "metadata": {},
+          "execution_count": 61
+        }
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "# 확인용 df 출력 셀\n",
+        "df"
+      ],
+      "metadata": {
+        "id": "uYFF5Jew0Xz7"
+      },
+      "execution_count": null,
+      "outputs": []
+    },
+    {
+      "cell_type": "markdown",
+      "metadata": {
+        "id": "5YmjKvYizyCb"
+      },
+      "source": [
+        "### 21. Given a DataFrame of random numeric values:\n",
+        "```python\n",
+        "df = pd.DataFrame(np.random.random(size=(5, 3))) # this is a 5x3 DataFrame of float values\n",
+        "```\n",
+        "\n",
+        "how do you subtract the row mean from each element in the row?"
+      ]
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "# 랜덤 시드 고정\n",
+        "np.random.seed(2025)\n",
+        "\n",
+        "df = pd.DataFrame(np.random.random(size=(5, 3)))\n",
+        "\n",
+        "\n"
+      ],
+      "metadata": {
+        "id": "EeAkDWv40e9J"
+      },
+      "execution_count": 65,
+      "outputs": []
+    },
+    {
+      "cell_type": "code",
+      "source": [
+        "# 각 행의 원소에서 각 행의 평균 빼기\n",
+        "result = df.sub(df.mean(axis=1), axis=0)\n",
+        "\n",
+        "# 계산된 결과 출력\n",
+        "result"
+      ],
+      "metadata": {
+        "id": "Z24qNGpgKEVi",
+        "colab": {
+          "base_uri": "https://localhost:8080/",
+          "height": 206
+        },
+        "outputId": "3deb31be-7835-4117-f6ba-f662e0321959"
+      },
+      "execution_count": 66,
+      "outputs": [
+        {
+          "output_type": "execute_result",
+          "data": {
+            "text/plain": [
+              "          0         1         2\n",
+              "0 -0.516494  0.235870  0.280624\n",
+              "1  0.081768  0.024435 -0.106204\n",
+              "2 -0.047373 -0.212124  0.259497\n",
+              "3  0.115235 -0.230544  0.115309\n",
+              "4 -0.229731  0.498009 -0.268278"
+            ],
+            "text/html": [
+              "\n",
+              "  <div id=\"df-93705122-5682-466e-a912-3df014107cf3\" class=\"colab-df-container\">\n",
+              "    <div>\n",
+              "<style scoped>\n",
+              "    .dataframe tbody tr th:only-of-type {\n",
+              "        vertical-align: middle;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe tbody tr th {\n",
+              "        vertical-align: top;\n",
+              "    }\n",
+              "\n",
+              "    .dataframe thead th {\n",
+              "        text-align: right;\n",
+              "    }\n",
+              "</style>\n",
+              "<table border=\"1\" class=\"dataframe\">\n",
+              "  <thead>\n",
+              "    <tr style=\"text-align: right;\">\n",
+              "      <th></th>\n",
+              "      <th>0</th>\n",
+              "      <th>1</th>\n",
+              "      <th>2</th>\n",
+              "    </tr>\n",
+              "  </thead>\n",
+              "  <tbody>\n",
+              "    <tr>\n",
+              "      <th>0</th>\n",
+              "      <td>-0.516494</td>\n",
+              "      <td>0.235870</td>\n",
+              "      <td>0.280624</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>1</th>\n",
+              "      <td>0.081768</td>\n",
+              "      <td>0.024435</td>\n",
+              "      <td>-0.106204</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>2</th>\n",
+              "      <td>-0.047373</td>\n",
+              "      <td>-0.212124</td>\n",
+              "      <td>0.259497</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>3</th>\n",
+              "      <td>0.115235</td>\n",
+              "      <td>-0.230544</td>\n",
+              "      <td>0.115309</td>\n",
+              "    </tr>\n",
+              "    <tr>\n",
+              "      <th>4</th>\n",
+              "      <td>-0.229731</td>\n",
+              "      <td>0.498009</td>\n",
+              "      <td>-0.268278</td>\n",
+              "    </tr>\n",
+              "  </tbody>\n",
+              "</table>\n",
+              "</div>\n",
+              "    <div class=\"colab-df-buttons\">\n",
+              "\n",
+              "  <div class=\"colab-df-container\">\n",
+              "    <button class=\"colab-df-convert\" onclick=\"convertToInteractive('df-93705122-5682-466e-a912-3df014107cf3')\"\n",
+              "            title=\"Convert this dataframe to an interactive table.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\" viewBox=\"0 -960 960 960\">\n",
+              "    <path d=\"M120-120v-720h720v720H120Zm60-500h600v-160H180v160Zm220 220h160v-160H400v160Zm0 220h160v-160H400v160ZM180-400h160v-160H180v160Zm440 0h160v-160H620v160ZM180-180h160v-160H180v160Zm440 0h160v-160H620v160Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "\n",
+              "  <style>\n",
+              "    .colab-df-container {\n",
+              "      display:flex;\n",
+              "      gap: 12px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert {\n",
+              "      background-color: #E8F0FE;\n",
+              "      border: none;\n",
+              "      border-radius: 50%;\n",
+              "      cursor: pointer;\n",
+              "      display: none;\n",
+              "      fill: #1967D2;\n",
+              "      height: 32px;\n",
+              "      padding: 0 0 0 0;\n",
+              "      width: 32px;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-convert:hover {\n",
+              "      background-color: #E2EBFA;\n",
+              "      box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "      fill: #174EA6;\n",
+              "    }\n",
+              "\n",
+              "    .colab-df-buttons div {\n",
+              "      margin-bottom: 4px;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert {\n",
+              "      background-color: #3B4455;\n",
+              "      fill: #D2E3FC;\n",
+              "    }\n",
+              "\n",
+              "    [theme=dark] .colab-df-convert:hover {\n",
+              "      background-color: #434B5C;\n",
+              "      box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "      filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "      fill: #FFFFFF;\n",
+              "    }\n",
+              "  </style>\n",
+              "\n",
+              "    <script>\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#df-93705122-5682-466e-a912-3df014107cf3 button.colab-df-convert');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      async function convertToInteractive(key) {\n",
+              "        const element = document.querySelector('#df-93705122-5682-466e-a912-3df014107cf3');\n",
+              "        const dataTable =\n",
+              "          await google.colab.kernel.invokeFunction('convertToInteractive',\n",
+              "                                                    [key], {});\n",
+              "        if (!dataTable) return;\n",
+              "\n",
+              "        const docLinkHtml = 'Like what you see? Visit the ' +\n",
+              "          '<a target=\"_blank\" href=https://colab.research.google.com/notebooks/data_table.ipynb>data table notebook</a>'\n",
+              "          + ' to learn more about interactive tables.';\n",
+              "        element.innerHTML = '';\n",
+              "        dataTable['output_type'] = 'display_data';\n",
+              "        await google.colab.output.renderOutput(dataTable, element);\n",
+              "        const docLink = document.createElement('div');\n",
+              "        docLink.innerHTML = docLinkHtml;\n",
+              "        element.appendChild(docLink);\n",
+              "      }\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "\n",
+              "  <div id=\"id_bffba77f-ac68-4dcf-a679-f2f954c47feb\">\n",
+              "    <style>\n",
+              "      .colab-df-generate {\n",
+              "        background-color: #E8F0FE;\n",
+              "        border: none;\n",
+              "        border-radius: 50%;\n",
+              "        cursor: pointer;\n",
+              "        display: none;\n",
+              "        fill: #1967D2;\n",
+              "        height: 32px;\n",
+              "        padding: 0 0 0 0;\n",
+              "        width: 32px;\n",
+              "      }\n",
+              "\n",
+              "      .colab-df-generate:hover {\n",
+              "        background-color: #E2EBFA;\n",
+              "        box-shadow: 0px 1px 2px rgba(60, 64, 67, 0.3), 0px 1px 3px 1px rgba(60, 64, 67, 0.15);\n",
+              "        fill: #174EA6;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate {\n",
+              "        background-color: #3B4455;\n",
+              "        fill: #D2E3FC;\n",
+              "      }\n",
+              "\n",
+              "      [theme=dark] .colab-df-generate:hover {\n",
+              "        background-color: #434B5C;\n",
+              "        box-shadow: 0px 1px 3px 1px rgba(0, 0, 0, 0.15);\n",
+              "        filter: drop-shadow(0px 1px 2px rgba(0, 0, 0, 0.3));\n",
+              "        fill: #FFFFFF;\n",
+              "      }\n",
+              "    </style>\n",
+              "    <button class=\"colab-df-generate\" onclick=\"generateWithVariable('result')\"\n",
+              "            title=\"Generate code using this dataframe.\"\n",
+              "            style=\"display:none;\">\n",
+              "\n",
+              "  <svg xmlns=\"http://www.w3.org/2000/svg\" height=\"24px\"viewBox=\"0 0 24 24\"\n",
+              "       width=\"24px\">\n",
+              "    <path d=\"M7,19H8.4L18.45,9,17,7.55,7,17.6ZM5,21V16.75L18.45,3.32a2,2,0,0,1,2.83,0l1.4,1.43a1.91,1.91,0,0,1,.58,1.4,1.91,1.91,0,0,1-.58,1.4L9.25,21ZM18.45,9,17,7.55Zm-12,3A5.31,5.31,0,0,0,4.9,8.1,5.31,5.31,0,0,0,1,6.5,5.31,5.31,0,0,0,4.9,4.9,5.31,5.31,0,0,0,6.5,1,5.31,5.31,0,0,0,8.1,4.9,5.31,5.31,0,0,0,12,6.5,5.46,5.46,0,0,0,6.5,12Z\"/>\n",
+              "  </svg>\n",
+              "    </button>\n",
+              "    <script>\n",
+              "      (() => {\n",
+              "      const buttonEl =\n",
+              "        document.querySelector('#id_bffba77f-ac68-4dcf-a679-f2f954c47feb button.colab-df-generate');\n",
+              "      buttonEl.style.display =\n",
+              "        google.colab.kernel.accessAllowed ? 'block' : 'none';\n",
+              "\n",
+              "      buttonEl.onclick = () => {\n",
+              "        google.colab.notebook.generateWithVariable('result');\n",
+              "      }\n",
+              "      })();\n",
+              "    </script>\n",
+              "  </div>\n",
+              "\n",
+              "    </div>\n",
+              "  </div>\n"
+            ],
+            "application/vnd.google.colaboratory.intrinsic+json": {
+              "type": "dataframe",
+              "variable_name": "result",
+              "summary": "{\n  \"name\": \"result\",\n  \"rows\": 5,\n  \"fields\": [\n    {\n      \"column\": 0,\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0.2600799877766293,\n        \"min\": -0.5164936717536524,\n        \"max\": 0.1152351926457702,\n        \"num_unique_values\": 5,\n        \"samples\": [\n          0.08176811556001623,\n          -0.22973101435186788,\n          -0.04737339527141471\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": 1,\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0.30921884463997473,\n        \"min\": -0.230543997014095,\n        \"max\": 0.4980088847671926,\n        \"num_unique_values\": 5,\n        \"samples\": [\n          0.02443549762640368,\n          0.4980088847671926,\n          -0.21212404323618994\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    },\n    {\n      \"column\": 2,\n      \"properties\": {\n        \"dtype\": \"number\",\n        \"std\": 0.23814416048884277,\n        \"min\": -0.26827787041532475,\n        \"max\": 0.2806238044548883,\n        \"num_unique_values\": 5,\n        \"samples\": [\n          -0.10620361318641997,\n          -0.26827787041532475,\n          0.25949743850760476\n        ],\n        \"semantic_type\": \"\",\n        \"description\": \"\"\n      }\n    }\n  ]\n}"
+            }
+          },
+          "metadata": {},
+          "execution_count": 66
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file