Question

How many bricks each of size 25 cm × 10 cm × 8 cm will be required to build a wall 5 m long, 3 m high and 16 cm thick, assuming that the volume of sand and cement used in the construction is negligible?

Answer 1

$$\begin{gathered} \mathrm{Dimension}\mathrm{of}\mathrm{a}\mathrm{brick}=25\mathrm{cm}\times 10\mathrm{cm}\times 8\mathrm{cm} \\ \mathrm{Volume}\mathrm{of}\mathrm{a}\mathrm{brick}=25\mathrm{cm}\times 10\mathrm{cm}\times 8\mathrm{cm} \\ =2000{\mathrm{cm}}^3 \\ \mathrm{Also},\mathrm{it}\mathrm{is}\mathrm{given}\mathrm{that}\mathrm{the}\mathrm{length}\mathrm{of}\mathrm{the}\mathrm{wall}\mathrm{is}5\mathrm{m} \\ =5\times 100\mathrm{cm}(\because 1\mathrm{m}=100\mathrm{cm}) \\ =500\mathrm{cm} \\ \mathrm{Height}\mathrm{of}\mathrm{the}\mathrm{wall}=3\mathrm{m} \\ =3\times 100\mathrm{cm}(\because 1\mathrm{m}=100\mathrm{cm}) \\ =300\mathrm{cm} \\ \mathrm{It}\mathrm{is}16\mathrm{cm}\mathrm{thick},\mathrm{i}.\mathrm{e}.,\mathrm{breadth}=16\mathrm{cm} \\ \mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{wall}=\mathrm{length}\times \mathrm{breadth}\times \mathrm{height}=500\times 300\times 16=2400000{\mathrm{cm}}^3 \\ \therefore \mathrm{The}\mathrm{number}\mathrm{of}\mathrm{bricks}\mathrm{needed}\mathrm{to}\mathrm{build}\mathrm{the}\mathrm{wall}=\frac{\mathrm{volume}\mathrm{of}\mathrm{the}\mathrm{wall}}{\mathrm{volume}\mathrm{of}\mathrm{a}\mathrm{brick}}=\frac{2400000{\mathrm{cm}}^3}{2000{\mathrm{cm}}^3}=1200 \end{gathered}$$