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    Question

    An inlet pipe can fill a tank in 15 minutes when

    there’s no leakage. However, due to a leak in the tank, it takes 21 minutes to fill it completely. How long would the leak alone take to empty the full tank?
    A 45 min Correct Answer Incorrect Answer
    B 52.5 min Correct Answer Incorrect Answer
    C 57.5 min Correct Answer Incorrect Answer
    D 60 min Correct Answer Incorrect Answer

    Solution

    Let the capacity of the tank = L.C.M and 15 and 21 = 105 units
    Then, efficiency of the inlet pipe = 105 ÷ 15 = 7 units/minute
    Combined efficiency of the inlet pipe with the leak = 105 ÷ 21 = 5 units/minute
    So, efficiency of the leak = 5 - 7 = 2 units/minute (outlet)
    So, time taken by the leak to empty the entire tank = 105 ÷ 2 = 52.5 minutes

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