New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    A large reservoir can be filled by two pipes, A and B,

    in 20 minutes and 30 minutes respectively. If both pipes are opened simultaneously, after how much time should pipe A be closed so that the remaining part of the reservoir is filled in 6 minutes by pipe B alone?
    A 6.5 min Correct Answer Incorrect Answer
    B 5.5 min Correct Answer Incorrect Answer
    C 9.6 min Correct Answer Incorrect Answer
    D 12 min Correct Answer Incorrect Answer

    Solution

    ATQ, Both pipes are opened simultaneously. Let after 'y' minutes, pipe A be closed. Then, the equation for the fill rate when both pipes are open and when pipe B finishes the job alone is: Pipe A should be closed after 9.6 minutes.

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