Question

18. A lane 180 m long and 5 m wide is to be paved with bricks, of length 20 cm and breadth 150
Find the cost of the bricks that are required, at the rate of 750 per thousand.​

Answer 1

Area of lane=area of rectangle

=180x5=900m²

Area of brick=0.2x0. 15

=0.03m²

No of bricks needed=900/0.03

=30000

Cost of bricks=30000/1000x750

=30x750=22500

Answer 2

We indicate with L length of the lane, with l breadth of the lane.

we calculate the area of ​​a lane:
A₁=L×l=180×5=900 m²

we indicate with b length of the brick , with h breadth of the brick.

we calculate the area of a brick:
A₂=b×h=20×150=3000 cm²

we convert the cm² in m² (1m²=10000 cm²)
3000 cm²=0,3 m²
then
A₂=0,3 m²

we calculate the required number of bricks:
n=A₁/A₂=900/0,3=3000 bricks
we calculate the total cost of bricks:
tot=(750×3000):1000=2250 ruppes