The diameters of the internal and external surfaces of a hollow spherical shell are 6 cm and 10 cm respectively. If it is melted and recast into a solid cylinder of diameter 14 cm, find the height of the cylinder.
Internal radius of the hollow spherical shell = 6/2 = 3cm
And external radius of that shell = 10/2 = 5cm
Radius of the cylinder = 14/2 = 7
Let height of the cylinder be x cm
According to the question,
Volume of the cylinder = volume of the spherical shell
∴ height of cylinder = 
cm
18