If two cylinders of the same lateral surface have their radii in the ratio 4 : 9, then the ratio of their heights is

1. 2 : 3

2. 3 : 2

3. 4 : 9

4. 9 : 4

The radii of two cylinders are in the ratio 2 : 3 and their heights are in the ratio 5 : 3. The ratio of their volumes is

1. 10 : 17

2. 20 : 27

3. 17 : 27

4. 20 : 37

If the diameter of the base of cone is 10 cm and its height is 12 cm, then its curved surface area is

1. 60π cm²

2. 65π cm²

3. 90π cm²

4. 120π cm²