Question

A vessel is in the form of a frustum of a cone. Its radius at top end is 8 cm and the bottom end is 12 cm. Its height is 21 cm. Find the volume of the frustum cone.

• A. 1,128 $\pi {cm}^3$
• B. 3,128 $\pi {cm}^3$
• C. 4,128 $\pi {cm}^3$
• D. 2,128 $\pi {cm}^3$

Answer 1

The correct option is D 2,128 $\pi {cm}^3$

Volume = $\frac{\pi h}{3}(R^2+Rr+r^2)$

= $\frac{\pi \times 21}{3}({12}^2+12\times 8+8^2)$

= $7\pi (144+96+64)$

= $7\pi \left(304\right)$

= $2,128c{m}^3$