Question

A wall 15 m long, 30 cm wide and 4 m high is made of bricks, each measuring 22 cm × 12.5 cm × 7.5 cm. If $\frac{1}{12}$ of the total volume of the wall consists of mortar, how many bricks are there in the wall?

Answer 1

Volume of the wall$=1500\times 30\times 400=18000000c{m}^3$
Total quantity of mortar$=\frac{1}{12}\times 18000000=1500000c{m}^3$
∴ Volume of the bricks$=18000000-1500000=16500000c{m}^3$

Volume of a single brick$=22\times 12.5\times 7.5=2062.5c{m}^3$

∴ Total number of bricks$=\frac{\mathrm{Total}\mathrm{volume}\mathrm{of}\mathrm{the}\mathrm{bricks}}{\mathrm{Volume}\mathrm{of}\mathrm{a}\mathrm{single}\mathrm{brick}}=\frac{16500000}{2062.5}=8000$ bricks