Question

A wall 24 m , 0.4 m thick and 6 m high is constructed with the bricks each of dimensions 25 cm $\times$ 16 cm $\times$ 10 cm . If the mortar occupies $\frac{1}{10}th$ of the volume of the wall, then find the number of bricks used in constructing the wall.

Answer 1

Dimensions of the wall are 24 m × 0.4 m × 6 m
Volume of the wall = 24 m × 0.4 m × 6 m = 57.6 m³
Dimensions of the bricks are 25 m × 16 m × 10 m
Volume of each brick = 4000 cm³ = 0.004 m³
Volume of mortar = $\frac{1}{10}\times Volumeofthewall=\frac{1}{10}\times 57.6=5.76m^3$
Volume of all the bricks = Volume of the wall − Volume of mortar
$$\begin{gathered} =57.6-5.76 \\ =51.84m^3 \end{gathered}$$
Let the number of bricks used in making the wall be n.
$$\begin{gathered} \frac{Volumeofallthebricks}{Volumeofeachbrick}=n \\ \Rightarrow \frac{51.84}{0.004}=n \\ \Rightarrow n=12960 \end{gathered}$$
Hence, 12960 bricks are used to make the wall.