A solid wooden toy is in the form of a hemisphere surmounted by a cone of same radius. The radius of hemisphere is 3.5 cm and the total wood used in the making of toy is . Find the height of the toy. Also, find the cost of painting the hemispherical part of the toy at the rate of ` 10 per cm2.

Let h be the height of the cone and r be radius of its base


Now, volume of the wooden toy =



According to the question,


⇒ h = 6cm


The height of the wooden toy = 6cm + 3.5 cm


= 9.5cm


Now, curved surface area of the hemispherical part = 2 π r2


= 2π × (3.5)2


=77cm2


Hence the cost of painting the hemispherical part of the toy at the rate of ` 10 per cm2 = 77 × 10 = Rs.770


32