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प्रश्न
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?
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उत्तर
\[\text { Dimension of a brick } = 25 cm \times 10 cm \times 8 cm\]
\[\text { Volume of a brick = 25 cm } \times 10 cm \times 8 cm\]
\[ = 2000 {cm}^3 \]
Also, it is given that the length of the wall is 5 m
\[ =5\times100 cm ( \because 1 m = 100 cm)\]
\[ =500 cm\]
\[ \text { Height of the wall = 3 m }\]
\[ =3\times100 cm ( \because 1 m = 100 cm)\]
\[ =300 cm\]
\[\text { It is 16 cm thick, i . e . , breadth = 16 cm } \]
\[{ \text { Volume of the wall = length }} \times \text { breadth }\times \text { height } = 500 \times 300 \times 16 = 2400000 {cm}^3 \]
\[ \therefore \text { The number of bricks needed to build the wall } = \frac{\text { volume of the wall }}{\text { volume of a brick }} = \frac{2400000 {cm}^3}{2000 {cm}^3} = 1200\]
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