The pool is filled with two pipes. If both pipes are open at the same time, then the pool is filled in 8 minutes.

| May 24, 2021 | education

The pool is filled with two pipes. If both pipes are open at the same time, then the pool is filled in 8 minutes. If only the first pipe is open, then the pool is filled in 20 minutes. How long will it take to fill the pool if only the second pipe is open?

We denote the capacity of the pool as 1.

Find out which part of the pool will be filled through 2 pipes in 1 minute.

We divide the entire volume of the pool by time.

1/8 = 1/8 of the pool.

The filling speed of the second pipe will be equal to:

1/20 = 1/20 of the pool per minute.

Determine the rate of filling through the 2nd pipe.

To do this, subtract the speed of 1 pipe from the joint speed.

1/8 – 1/20 = (common denominator 40) = 5/40 – 2/40 = 3/40 part per minute.

The filling time for 2 pipes will be equal to:

1 / 3/40 = 1 * 40/3 = 13 1/3 minutes.

Answer: In 13 1/3 minutes.



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