Question

If the height and radius of a cone are doubled the volume of the cone becomes

• A. 2 times
• B. 4 times
• C. 6 times
• D. 8 times

Answer 1

The correct option is D 8 times

let the Height of the cone=h am

Radius of the cone=r cm

Then volume of the cone$=\frac{1}{3}\pi r^{2}h$

If the height and radius are double then

Height=2h

Radius=2r

Then new volume$=\frac{1}{3}\pi (2r{)}^2\times 2h$

$\Rightarrow \frac{1}{3}\pi \times 4r\times 2h=8\times \frac{1}{3}\pi r^{2}h$

Hence it is 8 times of the old volume