Question

    Two inlet pipes can separately fill a cistern completely

    in 8 hours and 10 hours, respectively. They are operated for 2 hours, after which he second pipe is closed, and an outlet pipe which can drain out water from the full cistern in 20 hours is opened. How much time will it take to fill the cistern completely from the instant of opening the outlet pipe?
    A 7 hours Correct Answer Incorrect Answer
    B 8 hours Correct Answer Incorrect Answer
    C 7 hours 20 minutes Correct Answer Incorrect Answer
    D 8 hours 40 minutes Correct Answer Incorrect Answer

    Solution

    The correct answer is C

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