Question

    Pipes A and B can fill an empty tank in 20 hours and 24

    hours, respectively, while pipe C can drain the full tank in "x" hours. If all three pipes (A, B, and C) are opened together and can fill the tank in 15 hours, determine the value of "x."
    A 42 hrs Correct Answer Incorrect Answer
    B 48 hrs Correct Answer Incorrect Answer
    C 36 hrs Correct Answer Incorrect Answer
    D 40 hrs Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the capacity of the tank = 120 liters (LCM of 20, 24 and 15) Amount of water filled by pipe A in one hour = 120 ÷ 20 = 6 liters Amount of water filled by pipe B in one hour = 120 ÷ 24 = 5 liters Amount of water filled by pipes A, B and C together in one hour = 120 ÷ 15 = 8 liters Amount of water taken by pipes C alone in one hour = 6 + 5 – 8 = 3 liters Time taken by pipe C alone to empty the tank = 120 ÷3 = 40 hours

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