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    Question

    Pipe X can empty a completely filled tank in 60 hours.

    Pipe Y and X together can fill an empty tank completely in (z+6) hours. The efficiency of pipe Y is 40% more than the efficiency of pipe U. Pipe Y and U together can fill the empty tank together in 30 hours. Find the value of ‘z’.
    A 320 Correct Answer Incorrect Answer
    B 354 Correct Answer Incorrect Answer
    C 250 Correct Answer Incorrect Answer
    D 152 Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    ATQ,Let’s assume the capacity of the tank is 720 units. Efficiency of Pipe X = 720 / 60 = -12 units/hour. The efficiency of pipe Y is 40% more than the efficiency of pipe U. Let’s assume the efficiency of pipe U is ‘2b’. Efficiency of pipe Y = 2b of (100+40)% = 2b of 140% = 2.8b Pipe Y and U together can fill the empty tank together in 30 hours. (2.8b + 2b) x 30 = 720 4.8b = 24 b = 5 Pipe Y and X together can fill an empty tank completely in (z+6) hours. (2.8b - 12) x (z+6) = 720 (2.8x5 - 12) x (z+6) = 720 (14 - 12) x (z+6) = 720 2 x (z+6) = 720 (z+6) = 360 z = 354 Value of ‘z’ = 354.

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