Question

a cylindrical water tank of diameter 1.4m and height 2.1m is being fed by a pipe of diameter 3.5cm through which water flow at the rate of 2m/sec in how much time the tank will be filled

Answer 1

answer in above image

Answer 2

AnswEr:

Suppose the tank is filled in x minutes. Then,

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Volume of the water that flows out through the pipe in x minutes = Volume of the tank

$\implies \sf\pi \times ( \frac{3.5}{200}) {}^{2} \times (2 \times 60x) = \pi \times {(0.7)}^{2} \times 2.1 \\ \\ \implies \sf( \frac{35}{2000} ) {}^{2} \times (120x) = ( \frac{7}{10} ) {}^{2} \times ( \frac{21}{10} ) \\ \\ \implies \sf \: x = \frac{49 \times 21}{1000} \times \frac{2000 \times 2000}{35 \times 35 \times 120} \\ \\ \implies \sf = 49 \times 21 \times \frac{2000 \times 2}{35 \times 35 \times 120} \\ \\ \implies \tt \: 28 \: minutes$

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