If 2p = 3q = 4r then p : q : r is equal to:

1. 2 : 3 : 4

2. 3 : 4 : 6

3. 4 : 3 : 2

4. 6 : 4 : 3

The fourth proportional to 5, 8, 15 is :

1. 18

2. 20

3. 21

4. 24

The fourth proportional to 0.12, 0.21 and 8 is :

1. 8.9

2. 14

3. 17

4. 56