Pipe A can fill a tank in 40 minutes. Pipe B whose diameter is twice as that of Pipe A also fills the tank. lf both the pipes are opened together when the tank is 3/4ths empty, when will the tank be full?
Correct Answer: Description for Correct answer:
The ratio of the diameters of Pipe A and Pipe B is 1 : 2.
Therefore, the ratio of the rate of flow of water through A and B is 1 : 4
And the ratio of the time for Pipe A and Pipe B to fill a given capacity is 4 : 1.
If Pipe A can fill the tank in 40 minutes, then Pipe B will fill it in 10 minutes.
Together, the two pipes can fill \( \Large \frac{1}{40}+\frac{1}{10}=\frac{1+4}{10}=\frac{1}{8} \)th of tank in a minute.
They will take 8 minutes to fill tank.
Hence, to fill \( \Large \frac{3}{4} \)th of the tank, the two pipes will take \( \Large \frac{3}{4} \times 8 \) = 6minutes.
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