The radius of the internal and external surfaces of a hollow spherical shell are 3 cm and 5 cm respectively. If it is melted and recast into a solid cylinder of height cm. Find the diameter of the cylinder.

Volume of a sphere = (4/3)πr³

Volume of a cylinder = πr²h

Given, radius of the internal and external surfaces of a hollow spherical shell are 3 cm and 5 cm respectively. It is melted and recast into a solid cylinder of height cm.

Volume of material = Volume of the solid cylinder

⇒ r² = 49

⇒ r = 7 cm

Diameter = 14 cm