Bhanu Chaudhary
Poll
Professional
Asked: 2022-03-04T11:07:01+05:30

Pipe A alone can fill a tank in 8 minutes. Pipe B alone can fill the same tank in 12 minutes. Both the pipes are opened together when the tank is empty. However, Pipe B is closed 3 minutes before the tank is full. In what time did the tank get filled?

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Pipe A alone can fill a tank in 8 minutes. Pipe B alone can fill the same tank in 12 minutes. Both the pipes are opened together when the tank is empty. However, Pipe B is closed 3 minutes before the tank is full. In what time did the tank get filled?

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    1 Answer

    1. Professional

      Correct Answer: 6 minutes

      A Pipe A is kept open till the tank gets filled.

      Let the time for which Pipe A is kept open = t minutes

      Therefore, pipe B was kept open for (t – 3) minutes only.

      Pipe A fills 1/8th of the tank in a minute and pipe B fills 1/12th of the tank every minute.

      Together (A was open for t minutes and B for t-3 minutes) pipe A and pipe B fill ONE full tank

      i.e. t/8+t−3/12=1 or 3/t+2/t−6/24 or 5t=30 or 5=6minutes

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