If radii of two circular cylinders are in the ratio 3 : 4 and their heights are in the ratio 6 : 5, find the ratio of their curved surface areas.

The lateral surface area of a cube is 100 cm²; then its volume is :

1. 25 cm³

2. 125 cm³

3. 625 cm³

4. none of these

The radius of a cylinder is doubled and its height is halved; then the new volume is :

1. same

2. 2 times

3. 4 times

4. 8 times

The dimensions of a solid metallic cuboid are 9 cm x 8 cm x 3 cm. It is melted and recast into a cube. The edge of the cube so formed is :

1. 6 cm

2. 12 cm

3. 18 cm

4. 24 cm