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    Question

    Pipes ‘A’ and ‘B’ together can fill a tank in 18

    hours, while pipe ‘B’ alone can fill it in 36 hours. If pipe ‘C’ takes 12 hours less than pipe ‘A’ to fill the tank, then how much percent more/less efficient is pipe ‘C’ compared to pipe ‘B’?
    A 25% Correct Answer Incorrect Answer
    B 45% Correct Answer Incorrect Answer
    C 50% Correct Answer Incorrect Answer
    D 38% Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ, Let the capacity of the tank be 72 units (LCM of 18 and 36). Efficiency of pipes (A + B) = 72/18 = 4 units/hour. Efficiency of pipe ‘B’ = 72/36 = 2 units/hour. Efficiency of pipe ‘A’ = 4 - 2 = 2 units/hour. Time taken by pipe ‘A’ = 72/2 = 36 hours. Time taken by pipe ‘C’ = 36 - 12 = 24 hours. Efficiency of pipe ‘C’ = 72/24 = 3 units/hour. Required percentage = ((3 - 2)/2) × 100 = 50%. Final Answer: Pipe C is 50% more efficient than pipe B.

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