UPSC 2015 CDS II Math Paper

Let the height of the cylinder be h m.
Radius of the cylinder = Radius of the hemisphere = r = 12 m
∴

2

3

π×123+π×122×h=3312π
⇒8+h=

3312

144

=2323
⇒h=15m
Therefore, ratio of the surface areas of the spherical and cylindrical portions