Question

A washing tub in the shape of a frustum of a cone has height 21 cm. The radii of the circular top and bottom are 20 cm and 15 cm respectively. What is the capacity of the tub? = (π = 22/7 )

Answer 1

Given: For the frustum shaped tub, 

height (h) = 21 cm,

radii (r₁ ) = 20 cm, and (r₂ ) = 15 cm 

To find: Capacity (volume) of the tub. 

Volume of frustum = 1/3 πh (r₁² + r₂² + r₁ × r₂ )

= 1/3 x 22/7 x 21 (20² + 15² + 20 x 15)

= 22(400 + 225 + 300)

= 22 x 925

= 20350 cm³

= (20350/1000) liters    ....[1liter = 1000 cm³]

= 20.35 liters

∴ The capacity of the tub is 20.35 liters.