The radii of two circular faces of the frustum of a cone of height 21 cm are 3 cm and 2 cm respectively. What is the volume of the frustum of the cone in cm3 ( = 227 )?

Answer: Option D

Solution

Answer: Option D

Solution:

$$\begin{array}{rl}& \text{Volume}=\frac{1}{3}\pi \left(R^2+r^2+Rr\right)h\\ & =\frac{1}{3}\times \frac{22}{7}\times \left(9+4+6\right)\times 21\\ & =22\times 19\\ & =418\text{ c}{\text{m}}^3\end{array}$$