# 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.

**Question:**

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

**Solution:**

Volume of the wall $=1500 \times 30 \times 400=18000000 \mathrm{~cm}^{3}$

Total quantity of mortar $=\frac{1}{12} \times 18000000=1500000 \mathrm{~cm}^{3}$

$\therefore$ Volume of the bricks $=18000000-1500000=16500000 \mathrm{~cm}^{3}$

Volume of a single brick $=22 \times 12.5 \times 7.5=2062.5 \mathrm{~cm}^{3}$

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