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    Question

    Two pipes 'X' and 'Y' can fill a tank in 24 minutes and

    36 minutes, respectively, while a pipe 'Z' can empty the tank in 72 minutes. If all three pipes are opened simultaneously, how much time (in seconds) will it take to fill the tank?
    A 1,080 secs Correct Answer Incorrect Answer
    B 1,527 secs Correct Answer Incorrect Answer
    C 3,544 secs Correct Answer Incorrect Answer
    D 1,056 secs Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the capacity of tank be 72 litres (LCM of 24, 36, and 72)

    Efficiency of 'X' = 72 ÷ 24 = 3 litres/minute

    Efficiency of 'Y' = 72 ÷ 36 = 2 litres/minute

    Efficiency of 'Z' = 72 ÷ 72 = 1 litre/minute (outlet)

    Required time = 72 ÷ (3 + 2 - 1)

    = 72 ÷ 4 = 18 minutes = 18 × 60 = 1,080 seconds

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