A solid sphere and a solid hemi-sphere have the same total surface area. Find the ratio between their volumes.

Metallic spheres of radii 6 cm, 8 cm and 10 cm respectively are melted and recasted into a single solid sphere. Taking π = 3.1, find the surface area of the solid sphere formed.

A sphere and a cone have equal volumes and equal radii. The ratio between the radius and height of the cone is :

1. 3 : 4

2. 4 : 3

3. 4 : 1

4. 1 : 4

The radius and the height of a cone are in the ratio 2 : 1. The ratio between the volumes of a sphere and this cone (both having equal radii) is :

1. 1 : 4

2. 4 : 1

3. 8 : 1

4. 1 : 8