Question

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

Answer 1

Length of wall (l) =15 m

Width (b)=30 cm =0.3 m

Height (h)=4m

$\therefore$ Volume of the wall =lbh

$=15\times 0.3\times 4m^3=18m^3$

Volume of mortar

$=\frac{1}{12}of18m^3=\frac{3}{2}=1.5m^3$

$\therefore$ Volume of bricks $=18-1.5=16.5m^3$

Volume of one brick

==22 cm. $\times$ 12.5 cm. $\times$ 7.5 cm.

$=22\times 12.5\times 7.5c{m}^3$

$=2062.5c{m}^3=\frac{2062.5}{100\times 100\times 100}{m}^3$

$=0.0020625m^3$ No. of bricks $=\frac{\text{Total volume of bricks}}{\text{Volume of one brick}}$

$=\frac{16.5}{0.0020625}=\frac{165\times 10000000}{10\times 20625}$

=8000