Finding means of groups of columns that match a certain value in another column

Type Height Age BMI
0 160 14 17
0 161 15 17.2
0 162 16 17.4
0 163 17 17.6
1 164 18 17.8
1 165 19 18
1 166 20 18.2
1 167 21 18.4
2 168 22 18.6
2 169 23 18.8
2 170 24 19
2 171 25 19.2
3 172 26 19.4
3 173 27 19.6
3 174 28 19.8
3 175 29 20
0 175 28 24.1
0 174 27 24
0 174 26 23.9
0 174 25 23.8
1 174 24 23.7
1 174 23 23.6
1 174 22 23.5
1 174 21 23.4
2 174 20 23.3
2 174 19 23.2
2 174 18 23.1
2 174 17 23
3 174 16 22.9
3 174 15 22.8
3 174 14 22.7
3 174 13 22.6