Question

The height of a cone is 15$cm.$ If its volume is $1570{cm}^3,$ find the radius of the base.

• A. $12cm$
• B. $10cm$
• C. $15cm$
• D. $18cm$

Answer 1

The correct option is B $10cm$

We know,

Volume of cone $=\frac{1}{3}\pi r^{2}h$.

Given, $h=15cm$

and $V=1570c{m}^3$

Then,

$\frac{1}{3}\times \frac{22}{7}\times r^2\times 15=1570$

$⟹$ $r^2=\frac{1570\times 3\times 7}{15\times 22}$ $=99.909$

$⟹$$r=$ $\sqrt{99.909}$ $\approx 10cm.$

Therefore, option $B$ is correct.