Question

The height of a right circular cylinder with lateral surface area $792c{m}^2$ is $21cm$. The diameter of the base is

• A. $3cm$
• B. $6cm$
• C. $11cm$
• D. $24cm$

Answer 1

The correct option is C $11cm$

Let the radius of the base $=rcm$

Therefore, the lateral surface area of cylinder$=2\pi rh$

$792=2\times \frac{22}{7}\times r\times 21$

$r=\frac{729\times 7}{2\times 22\times 21}$
$r=5.522cm$

Diameter of the base $=2r=2\times 5.522\approx 11cm$