Krish is 5 years younger than Parthiv. Eight years ago three times the age of Krish was 10 more than twice the age of Parthiv. Find Krish's present age?
A shuttle cock used for playing badminton has the shape of a frustum of a cone mounted on a hemisphere. The external diameters of the frustum are 5cm and 2cm, the height of the entire shuttle cock is 7cm. Find the external surface area.