To make a wall of length 6 metres, of height 5 metres and of thickness 0.5 metre, how many bricks of size `25 cm xx 12.5 xx 7.5 cm` will be required when `1/20` part of the wall will be made of a mixture of sand and cement?

Explanation

The volume of the wall `= 6 xx 5 xx 0.5` cubic - metres = 15 cu -metres.
Also, volume of each brick `=25 xx 12.5 xx 7.5 c c.= 0.25xx 0.125 xx 0.075` cu-metres
`=25/100 xx 25/1000 xx 75/ 1000 "cu-metres"= 3/1280` cu - metres
As per question, `x xx 3/1280 =(1-1/20)xx 15`
or, `x xx 3/1280 = 19/20 xx 15 or, x = 19/20 xx 15 xx 1280/3or, x = 6080`
Hence 6080 bricks will be required.