# Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. What is the total time required to fill the tank? (a). 10 min 20 sec (b). 11 min 45 sec (c). 12 min 30 sec (d). 14 min 40 sec

By BYJU'S Exam Prep

Updated on: September 25th, 2023

It is given that

Time is taken to fill a tank by pipe A = 15 minutes

Time is taken to fill a tank by pipe B = 20 minutes

Both pipes are opened together

Time at which pipe A is turned off = 4 minutes

So the part filled in 4 minutes = 4 (1/15 + 1/20)

By further calculation

= 7/15

The remaining part will be = 1 – 7/15 = 8/15

Part filled by B in 1 minute = 1/20

The ratio will be

1/20: 8/15:: 1: x

We get

x = (8/15 x 1 x 20) = 10 ⅔ min = 10 minutes 40 seconds

Total time required to fill the tank = 4 minutes + 10 minutes + 40 seconds = 14 minutes 40 seconds

Therefore, the total time required to fill the tank is 14 minutes and 40 seconds.

Summary:

## Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. What is the total time required to fill the tank? (a). 10 min 20 sec (b). 11 min 45 sec (c). 12 min 30 sec (d). 14 min 40 sec

Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. The total time required to fill the tank is 14 minutes and 40 seconds.

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