Question

If the radius and the height of a right circular cylinder are doubled, its volume becomes ________.

• A. $2$ times
• B. $3$ times
• C. $4$ times
• D. $8$ times

Answer 1

Answer: (D)

$8$ times

Let $V_1$, be the initial, then $V_1$=$\pi r^{2}h$

Now, new radius $=2r$ & height $=2h$

$\therefore$ New volume, $V_2$=$\pi {\left(2r\right)}^2\times 2h=8\pi r^{2}h=$ $8V_1$

Hence, now volume will become $8$ times.