Question

A lane 150 m long and 9 m wide is to be paved with bricks, each measuring 22.5 cm by 7.5 cm. How many bricks are required?
(a) 65000
(b) 70000
(c) 75000
(d) 80000

Answer 1

(d) 80000
Length of the road = 150 m = 15000 cm
Breadth of the road = 9 m = 900 cm
Area of the road = (Length × Breadth)
= (15000 × 900) cm²
= 13500000 cm²

Length of the brick = 22.5 cm
Breadth of the brick = 7.5 cm
Area of one brick = (Length × Breadth)
= ( 22.5 × 7.5 ) cm²
= 168.75 cm²

$$\begin{gathered} \mathrm{Number}\mathrm{of}\mathrm{bricks}=\frac{\mathrm{Area}\mathrm{of}\mathrm{the}\mathrm{road}}{\mathrm{Area}\mathrm{of}\mathrm{one}\mathrm{brick}} \\ =\frac{13500000{\mathrm{cm}}^2}{168.75{\mathrm{cm}}^2}=80000\mathrm{bricks} \end{gathered}$$