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

\[\text { Dimension of a brick } = 25 cm \times 10 cm \times 8 cm\]

\[\text { Volume of a brick = 25 cm } \times 10 cm \times 8 cm\]

\[ = 2000 {cm}^3 \]

Also, it is given that the length of the wall is 5 m

\[ =5\times100 cm ( \because 1 m = 100 cm)\]

\[ =500 cm\]

\[ \text { Height of the wall = 3 m }\]

\[ =3\times100 cm ( \because 1 m = 100 cm)\]

\[ =300 cm\]

\[\text { It is 16 cm thick, i . e . , breadth = 16 cm } \]

\[{ \text { Volume of the wall = length }} \times \text { breadth }\times \text { height } = 500 \times 300 \times 16 = 2400000 {cm}^3 \]

\[ \therefore \text { The number of bricks needed to build the wall } = \frac{\text { volume of the wall }}{\text { volume of a brick }} = \frac{2400000 {cm}^3}{2000 {cm}^3} = 1200\]