A wall 9 m long, 6 m high and 20 cm thick, is to be constructed using bricks of dimensions 30 cm, 15 cm and 10 cm. How many bricks will be required ?

Given:

The length of the wall = 9 m.

The height of the wall = 6 m.

The breadth of the wall = 20 cm = 0.2 m.

As we know that volume of wall = length x breadth x height

= 9 x 6 x 0.2 m³

= 10.8 m³

The length of the brick = 30 cm = 0.3 m.

The breadth of the brick = 15 cm = 0.15 m.

The height of the brick = 10 cm = 0.1 m.

As we know that volume of one brick = length x breadth x height

= 0.3 x 0.15 x 0.1 m³

= 0.0045 m³

Let a be the number of bricks.

Number of bricks = $\dfrac{Volume of wall}{ Volume of one brick}$

⇒ a = $\dfrac{10.8}{0.0045}$

⇒ a = $\dfrac{108000}{45}$

⇒ a = 2400

Hence, the number of bricks required to construct the wall is 2400.