Question

    Pipes 'G' and 'H' can fill a tank in 24 hours and 8

    hours respectively, while pipe 'I' can empty it in 48 hours. All pipes are opened together when the tank was empty. After 3 hours, pipe 'G' is closed. Find the total time taken to fill the tank.
    A 12.5 hrs Correct Answer Incorrect Answer
    B 8.4 hrs Correct Answer Incorrect Answer
    C 18.9 hrs Correct Answer Incorrect Answer
    D 20 hrs Correct Answer Incorrect Answer

    Solution

    ATQ, Tank capacity = 240 units Efficiency of pipe 'G' = 240 / 24 = 10 units/hour Efficiency of pipe 'H' = 240 / 8 = 30 units/hour Efficiency of pipe 'I' = 240 / 48 = 5 units/hour Tank filled in 3 hours = (10 + 30 - 5) × 3 = 105 units Time taken by pipes 'H' and 'I', together to fill the remaining part of tank = (240 - 105) /(30-5) = 5.4 Total time taken = 3 + 5.4 = 8.4 hours

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