Question

A cistern, internally measuring 150 cm x 120 cm x 110 cm, has 129600 cu.cm of water in it. Porous bricks are placed in the water until the cistern is full to the brim. Each brick absorbs one-seventeenth of its own volume of water. How many bricks can be put in without overflowing the water, each brick being 22.5 cm x 7.5 cm x 6.5 cm?

Answer 1

Total volume of cistern=`150*120*110=1980000cm^3`
Volume of each brick=`225*7.5*6.5=1096.875cm^3`
Net increase in volume of bricks=`1096.875-1/17*1096.875`
`=16/17*1096.875cm^3`
Let n number of bricks put inside cisten without overflowing
`n*16/17*1096.875`
`n=1729.410`
1729 bricks put down inside the cistern without overflowing.