How many bricks, each measuring (25 cm × 11.25 cm × 6 cm),
Question:

How many bricks, each measuring (25 cm × 11.25 cm × 6 cm), will be required to construct a wall (8 m × 6 m × 22.5 cm)?
(a) 8000
(b) 6400
(c) 4800
(d) 7200

Solution:

(b) 6400

Volume of the wall $=(800 \times 600 \times 22.5) \mathrm{cm}^{3}$

Volume of each brick $=(25 \times 11.25 \times 6) \mathrm{cm}^{3}$

Number of bricks $=\frac{\text { Volume of the wall }}{\text { Volume of each brick }}$

$=\frac{800 \times 600 \times 22.5}{25 \times 11.25 \times 6}$

$=6400$