If A : B = 2 : 5 and B : C = 4 : 5, then C : A = ?

1. 5 : 2
2. 2 : 1
3. 15 : 8
4. 25 : 8

By increasing 91 in the ratio 7 : 13, we get :

1. 182
2. 169
3. 121
4. 116

The third proportional to 9 and 18 is

1. 21
2. 24
3. 27
4. 36

The mean proportional between 5 and 45 is

1. 10
2. 12
3. 15
4. 25