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 cone and a sphere have equal volumes. Their radii are also equal each being 10 cm; the height of the cone is :

1. 70 cm

2. 40 cm

3. 50 cm

4. 20 cm

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

A solid metallic cylinder is melted and formed into identical solid cones each having same radius and same height as that of the cylinder. The number of cones formed is :

1. 3

2. 6

3. 9

4. 2