Eight identical metallic spheres, each of radius 1 cm are melted and recast into a solid sphere. The radius of the solid sphere formed is :

1. 3 cm

2. 2 cm

3. 1.5 cm

4. 2.5 cm

The ratio between the heights of two solid cones is 2 : 3 and ratio between their radii is 9 : 8. The ratio between their volumes is :

1. 27 : 32

2. 32 : 27

3. 3 : 2

4. 2 : 3

The volume of a solid cylinder and a solid cone are same. If their radii are also same, the ratio between the heights of cylinder and cone is :

1. 3 : 1

2. 2 : 3

3. 1 : 3

4. 3 : 2

The radius of a solid cylinder is doubled keeping the height same. The percentage increase in its volume is :

1. 200%

2. 100%

3. 400%

4. 300%