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 = \[\frac{1}{10} \times \text { Volume of the wall } = \frac{1}{10} \times 57 . 6 = 5 . 76 m^3\]

Volume of all the bricks = Volume of the wall − Volume of mortar

\[= 57 . 6 - 5 . 76\]

\[ = 51 . 84 m^3\]

Let the number of bricks used in making the wall be n.

\[\frac{\text { Volume of all the bricks }}{\text { Volume of each brick }} = n\]

\[ \Rightarrow \frac{51 . 84}{0 . 004} = n\]

\[ \Rightarrow n = 12960\]

Hence, 12960 bricks are used to make the wall.