Question

How many bricks of length, breadth and height 20 cm, 12 cm and 7.5 cm, respectively, will be required to build a wall 4.8 m long, 30 cm thick and 3 m high?

Answer 1

Length of a brick = 20 cm
Breadth of a brick = 12 cm
Height of a brick = 7.5 cm
Volume of the brick = length × breadth × height
= 20 × 12 × 7.5 cm³
= 1800 cm³
Length of the wall = 4.8 m = 480 cm (1 m = 100 cm)
Breadth of the wall = 30 cm
Height of the wall = 3 m = 300 cm
Volume of the wall = length × breadth × height
= 480 × 30 × 300 cm³
= 4320000 cm³
∴ Number of bricks required $=\frac{\mathrm{Volume}\mathrm{of}\mathrm{wall}}{\mathrm{Volume}\mathrm{of}\mathrm{brick}}$
$=\frac{4320000}{1800}$
= 2400 bricks
∴ 2400 bricks will be needed to build the wall.