Q18 of 47 Page 1

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 .


Given radius of hemisphere = 3.5cm


Also, radius of cone = 3.5cm


Let the height of the cone be h cm.


Volume of wood used = Volume of hemisphere + Volume of cone


⇒


⇒ ⇒ ⇒ ⇒


Total height of the toy = Height of the cone + Radius of hemisphere


So,total height = 6 + 3.5 = 9.5cm


Area of the hemispherical surface = 2πr2 =


∴ Cost of painting = (77 × 10) = 770


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