Question

A brick measures $20cm\times 10cm\times 5cm$. How many bricks will be required for a wall $20m$ long, $2m$ high and $\frac{1}{2}m$ thick?

• A. $10000$
• B. $12000$
• C. $20000$
• D. $17500$

Answer 1

The correct option is C

$20000$

Volume of the brick of length, $l$, breadth, $b$ and height, $h$ is $lbh$

$=20\times 10\times 5=1000c{m}^3$

Similarly,

Volume of the wall $=20\times 2\times \frac{1}{2}=20m^3=20000000c{m}^3$ [$\because 1m=100cm\therefore 1m^3=1000000c{m}^3$]

Now, number of bricks required $=\frac{\text{Volume of the wall}}{\text{Volume of the brick}}$

$=\frac{20000000}{1000}=20000$