Q13 of 227 Page 897

A hemisphere of lead of radius 9 cm is into a right circular cone of height 72cm. Find the radius of the base of the cone.

Volume of hemisphere of radius 9 cm


= × π × 9 × 9 × 9cm3


Volume of circular cone (height = 72 cm)


× π × r2 × 72cm


Volume of cone = volume of hemisphere


× π × r2 × 72 = π × 9 × 9 × 9


r2 = π × 9 × 9 × 9 × π = 20.25


r = = 4.5cm


Hence, radius of the base of the cone = 4.5 cm


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