diff --git a/ml2/3_5_Exercise_1.ipynb b/ml2/3_5_Exercise_1.ipynb
index c8db13d..0a9660d 100644
--- a/ml2/3_5_Exercise_1.ipynb
+++ b/ml2/3_5_Exercise_1.ipynb
@@ -46,7 +46,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 11,
+   "execution_count": null,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -72,7 +72,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Assign the variable *df* a Dataframe with the Titanic Dataset from the URL https://raw.githubusercontent.com/gsi-upm/sitc/master/ml2/data-titanic/train.csv\"\n",
+    "Assign the variable *df* a Dataframe with the Titanic Dataset from the URL https://raw.githubusercontent.com/gsi-upm/sitc/master/ml2/data-titanic/train.csv.\n",
     "\n",
     "Print *df*."
    ]
@@ -209,312 +209,9 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 20,
-   "metadata": {},
-   "outputs": [
-    {
-     "data": {
-      "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>PassengerId</th>\n",
-       "      <th>Survived</th>\n",
-       "      <th>Pclass</th>\n",
-       "      <th>Name</th>\n",
-       "      <th>Sex</th>\n",
-       "      <th>Age</th>\n",
-       "      <th>SibSp</th>\n",
-       "      <th>Parch</th>\n",
-       "      <th>Ticket</th>\n",
-       "      <th>Fare</th>\n",
-       "      <th>Cabin</th>\n",
-       "      <th>Embarked</th>\n",
-       "      <th>FamilySize</th>\n",
-       "      <th>AgeGroup</th>\n",
-       "      <th>Deck</th>\n",
-       "    </tr>\n",
-       "  </thead>\n",
-       "  <tbody>\n",
-       "    <tr>\n",
-       "      <th>0</th>\n",
-       "      <td>1</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3</td>\n",
-       "      <td>Braund, Mr. Owen Harris</td>\n",
-       "      <td>male</td>\n",
-       "      <td>22.0</td>\n",
-       "      <td>1</td>\n",
-       "      <td>0</td>\n",
-       "      <td>A/5 21171</td>\n",
-       "      <td>7.2500</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>S</td>\n",
-       "      <td>1</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>X</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>1</th>\n",
-       "      <td>2</td>\n",
-       "      <td>1</td>\n",
-       "      <td>1</td>\n",
-       "      <td>Cumings, Mrs. John Bradley (Florence Briggs Th...</td>\n",
-       "      <td>female</td>\n",
-       "      <td>38.0</td>\n",
-       "      <td>1</td>\n",
-       "      <td>0</td>\n",
-       "      <td>PC 17599</td>\n",
-       "      <td>71.2833</td>\n",
-       "      <td>C85</td>\n",
-       "      <td>C</td>\n",
-       "      <td>1</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>C</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>2</th>\n",
-       "      <td>3</td>\n",
-       "      <td>1</td>\n",
-       "      <td>3</td>\n",
-       "      <td>Heikkinen, Miss. Laina</td>\n",
-       "      <td>female</td>\n",
-       "      <td>26.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>STON/O2. 3101282</td>\n",
-       "      <td>7.9250</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>S</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>X</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>3</th>\n",
-       "      <td>4</td>\n",
-       "      <td>1</td>\n",
-       "      <td>1</td>\n",
-       "      <td>Futrelle, Mrs. Jacques Heath (Lily May Peel)</td>\n",
-       "      <td>female</td>\n",
-       "      <td>35.0</td>\n",
-       "      <td>1</td>\n",
-       "      <td>0</td>\n",
-       "      <td>113803</td>\n",
-       "      <td>53.1000</td>\n",
-       "      <td>C123</td>\n",
-       "      <td>S</td>\n",
-       "      <td>1</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>C</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>4</th>\n",
-       "      <td>5</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3</td>\n",
-       "      <td>Allen, Mr. William Henry</td>\n",
-       "      <td>male</td>\n",
-       "      <td>35.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>373450</td>\n",
-       "      <td>8.0500</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>S</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>X</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>...</th>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "      <td>...</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>886</th>\n",
-       "      <td>887</td>\n",
-       "      <td>0</td>\n",
-       "      <td>2</td>\n",
-       "      <td>Montvila, Rev. Juozas</td>\n",
-       "      <td>male</td>\n",
-       "      <td>27.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>211536</td>\n",
-       "      <td>13.0000</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>S</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>X</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>887</th>\n",
-       "      <td>888</td>\n",
-       "      <td>1</td>\n",
-       "      <td>1</td>\n",
-       "      <td>Graham, Miss. Margaret Edith</td>\n",
-       "      <td>female</td>\n",
-       "      <td>19.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>112053</td>\n",
-       "      <td>30.0000</td>\n",
-       "      <td>B42</td>\n",
-       "      <td>S</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>B</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>888</th>\n",
-       "      <td>889</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3</td>\n",
-       "      <td>Johnston, Miss. Catherine Helen \"Carrie\"</td>\n",
-       "      <td>female</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>1</td>\n",
-       "      <td>2</td>\n",
-       "      <td>W./C. 6607</td>\n",
-       "      <td>23.4500</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>S</td>\n",
-       "      <td>3</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>X</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>889</th>\n",
-       "      <td>890</td>\n",
-       "      <td>1</td>\n",
-       "      <td>1</td>\n",
-       "      <td>Behr, Mr. Karl Howell</td>\n",
-       "      <td>male</td>\n",
-       "      <td>26.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>111369</td>\n",
-       "      <td>30.0000</td>\n",
-       "      <td>C148</td>\n",
-       "      <td>C</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>C</td>\n",
-       "    </tr>\n",
-       "    <tr>\n",
-       "      <th>890</th>\n",
-       "      <td>891</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3</td>\n",
-       "      <td>Dooley, Mr. Patrick</td>\n",
-       "      <td>male</td>\n",
-       "      <td>32.0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>0</td>\n",
-       "      <td>370376</td>\n",
-       "      <td>7.7500</td>\n",
-       "      <td>NaN</td>\n",
-       "      <td>Q</td>\n",
-       "      <td>0</td>\n",
-       "      <td>3.0</td>\n",
-       "      <td>X</td>\n",
-       "    </tr>\n",
-       "  </tbody>\n",
-       "</table>\n",
-       "<p>891 rows × 15 columns</p>\n",
-       "</div>"
-      ],
-      "text/plain": [
-       "     PassengerId  Survived  Pclass  \\\n",
-       "0              1         0       3   \n",
-       "1              2         1       1   \n",
-       "2              3         1       3   \n",
-       "3              4         1       1   \n",
-       "4              5         0       3   \n",
-       "..           ...       ...     ...   \n",
-       "886          887         0       2   \n",
-       "887          888         1       1   \n",
-       "888          889         0       3   \n",
-       "889          890         1       1   \n",
-       "890          891         0       3   \n",
-       "\n",
-       "                                                  Name     Sex   Age  SibSp  \\\n",
-       "0                              Braund, Mr. Owen Harris    male  22.0      1   \n",
-       "1    Cumings, Mrs. John Bradley (Florence Briggs Th...  female  38.0      1   \n",
-       "2                               Heikkinen, Miss. Laina  female  26.0      0   \n",
-       "3         Futrelle, Mrs. Jacques Heath (Lily May Peel)  female  35.0      1   \n",
-       "4                             Allen, Mr. William Henry    male  35.0      0   \n",
-       "..                                                 ...     ...   ...    ...   \n",
-       "886                              Montvila, Rev. Juozas    male  27.0      0   \n",
-       "887                       Graham, Miss. Margaret Edith  female  19.0      0   \n",
-       "888           Johnston, Miss. Catherine Helen \"Carrie\"  female   NaN      1   \n",
-       "889                              Behr, Mr. Karl Howell    male  26.0      0   \n",
-       "890                                Dooley, Mr. Patrick    male  32.0      0   \n",
-       "\n",
-       "     Parch            Ticket     Fare Cabin Embarked  FamilySize  AgeGroup  \\\n",
-       "0        0         A/5 21171   7.2500   NaN        S           1       3.0   \n",
-       "1        0          PC 17599  71.2833   C85        C           1       3.0   \n",
-       "2        0  STON/O2. 3101282   7.9250   NaN        S           0       3.0   \n",
-       "3        0            113803  53.1000  C123        S           1       3.0   \n",
-       "4        0            373450   8.0500   NaN        S           0       3.0   \n",
-       "..     ...               ...      ...   ...      ...         ...       ...   \n",
-       "886      0            211536  13.0000   NaN        S           0       3.0   \n",
-       "887      0            112053  30.0000   B42        S           0       3.0   \n",
-       "888      2        W./C. 6607  23.4500   NaN        S           3       NaN   \n",
-       "889      0            111369  30.0000  C148        C           0       3.0   \n",
-       "890      0            370376   7.7500   NaN        Q           0       3.0   \n",
-       "\n",
-       "    Deck  \n",
-       "0      X  \n",
-       "1      C  \n",
-       "2      X  \n",
-       "3      C  \n",
-       "4      X  \n",
-       "..   ...  \n",
-       "886    X  \n",
-       "887    B  \n",
-       "888    X  \n",
-       "889    C  \n",
-       "890    X  \n",
-       "\n",
-       "[891 rows x 15 columns]"
-      ]
-     },
-     "execution_count": 20,
-     "metadata": {},
-     "output_type": "execute_result"
-    }
-   ],
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
    "source": [
     "df['FamilySize'] = df['SibSp'] + df['Parch']\n",
     "df"
@@ -606,23 +303,9 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
-   "metadata": {
-    "collapsed": true
-   },
-   "outputs": [
-    {
-     "ename": "NameError",
-     "evalue": "name 'df' is not defined",
-     "output_type": "error",
-     "traceback": [
-      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
-      "\u001b[0;31mNameError\u001b[0m                                 Traceback (most recent call last)",
-      "\u001b[0;32m<ipython-input-2-515fd9f54fd1>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m     13\u001b[0m                 \u001b[0;32melse\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     14\u001b[0m                     \u001b[0;32mreturn\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'Others'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 15\u001b[0;31m \u001b[0mdf\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m'Salutation'\u001b[0m\u001b[0;34m]\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mdf\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m'Salutation'\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mapply\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mgroup_salutation\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     16\u001b[0m \u001b[0mdf\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mgroupby\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m'Salutation'\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0msize\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
-      "\u001b[0;31mNameError\u001b[0m: name 'df' is not defined"
-     ]
-    }
-   ],
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
    "source": [
     "def group_salutation(old_salutation):\n",
     "    if old_salutation == 'Mr':\n",
@@ -689,7 +372,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 12,
+   "execution_count": null,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -712,7 +395,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": null,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -805,7 +488,7 @@
    "window_display": false
   },
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
   },
@@ -819,7 +502,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.8"
+   "version": "3.8.12"
   },
   "latex_envs": {
    "LaTeX_envs_menu_present": true,