Find the number of bricks, each measuring 20 cm × 10 cm × 7.5 cm required to construct a wall 5 m long, 30 cm wide and 3 m high.

Length of brick = 20 cm

Breadth of brick = 10 cm

Height of brick = 7.5 cm

Brick is in the shape of a cuboid

Volume of cuboid = length × breadth × height

⇒ volume of 1 brick = 20 × 10 × 7.5

= 1500 cm³

Let n bricks be required to make the wall

Length of wall = 5 m = 500 cm

Breadth of wall = 30 cm

Height of wall = 3 m = 300 cm

Volume of wall = 500 × 30 × 300

= 4500000 cm³

The wall is completely made from bricks therefore

Volume of n bricks = volume of wall

⇒ n × volume of one brick = 56100000

⇒ n × 1500 = 4500000

⇒ n =

⇒ n =

⇒ n = 3000

Number of brick required = 3000