Question

A conical tomb is made up of bricks whose surface area is 5 m${}^2$. The slant height and radius of the tomb are measured to be 25 m and 7 m respectively. The approximate number of bricks used to construct the tomb are ____ (Take $\pi =\frac{22}{7}$)

• A. 100
• B. 110
• C. 150
• D. 160

Answer 1

The correct option is B

110

Given,
Surface area of bricks $=5m^2$
Slant height of the conical tomb, $l=25m$
Radius of the conical tomb, $r=7m$

$\therefore$ Curved surface area of the tomb $=\pi rl$
$=\frac{22}{7}\times 7\times 25$
$=550m^2$

$\therefore$ Number of bricks required $=\frac{\text{Curved surface area of tomb}}{\text{Front surface area of bricks}}$
$=\frac{550m^2}{5m^2}=110$ bricks