Question

How many bricks each of size 25 cm × 10 cm × 8 cm will be required to build a wall 5 m long, 3 m high and 16 cm thick, assuming that the volume of sand and cement used in the construction is negligible?

Answer 1

Dimension of a brick$=25cm\times 10cm\times 8cm$
Volume of a brick$=25cm\times 10cm\times 8cm$
$=2000c{m}^3$

Also, it is given that the length of the wall is 5 m =5×100 cm (∵1 m= 100 cm)
=500 cm

Height of the wall=3 m
=3×100 cm (∵ 1 m= 100 cm)
=300 cm

It is 16 cm thick, i.e., breadth =16 cm
Volume of the wall $=$ length $\times$ breadth$\times$height
$=500\times 300\times 16=2400000c{m}^3$
∴ The number of bricks needed to build the wall=$\frac{\text{volume of the wall}}{\text{volume of a brick}}$
$=\frac{2400000}{2000}=1200$