A wall 15 m long, 30 cm wide and 4 m high is made of bricks, each measuring 22 cm x 12.5 cm x 7.5 cm. If 
of the total volume of the wall consists of mortar, how many 12bricks are there in the wall?
Hint. Volume of bricks in the wall = {(1500 x 30 x 400) 
x (1500 x 30 x 400)1 cm3.
We know that,
Volume of cuboid = Length × Breadth × Height
Therefore,
Volume of the wall = 1500 × 30 × 400
= 18000000 cm3
Total quantity of mortar = 
= 1500000 cm3
Therefore,
Volume of bricks = 18000000 – 1500000
= 16500000 cm3
Now,
Volume of a single brick = 22 × 12.56 × 7.5
= 2062.5 cm3
Therefore,
Total number of bricks = 
= 
= 8000 bricks
10