Question

    Three pipe P1, P2 and P3 fill the tank in 15 hours, 10

    hours and 20 hours respectively. If all the three pipes opened together and pipe P2 & P1 are closed after three hours, then pipe P3 fill the remaining tank. Find the total time to fill whole tank.
    A 12 hours Correct Answer Incorrect Answer
    B 6 hours Correct Answer Incorrect Answer
    C 14 hours Correct Answer Incorrect Answer
    D 10 hours Correct Answer Incorrect Answer
    E 17 hours Correct Answer Incorrect Answer

    Solution

    Let the capacity of tank L.C.M. (15, 10, 20) = 60 units Efficiency of pipe P1 = 60/15 = 4 units/hour Efficiency of pipe P2 = 60/10 = 6 units/hour Efficiency of pipe P3 = 60/20 = 3 4 units/hour Tank filled by all the three in three hours = 13 × 3 = 39 units Remaining tank filled by pipe P3 = (60−39)/3 = 7 hours Total time = 3 + 7 = 10 hours

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