The diameters of internal and external surfaces of a hollow spherical shell are 10 cm and 6 cm respectively. If it is melted and recast into a solid cylinder of length of 
cm, find the diameter of the cylinder.
Diameter of internal surface =10 cm
∴ Radius of internal surface 
cm =5 cm
Diameter of external surface =6 cm
∴ Radius of external surface 
cm =3 cm
Volume of spherical shell hollow = 
Height of solid cylinder 
cm
Let the radius of the solid cylinder be ‘r’ cm
Volume of the solid cylinder 
Volume of the solid cylinder = Volume of spherical shell hollow
⇒ r2 × (8/3) = (4/3) × 98
⇒ r = 7
Diameter of cylinder = 14
cm
37