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    Question

    Pipe ‘A’ can fill a 210-litre tank in 21 hours. If

    pipe ‘A’ is 25% more efficient than pipe ‘C’ whereas pipe ‘B’ is 50% more efficient than pipe ‘C’, then find the time (in minutes) taken by all the given three pipes to fill the same tank together.
    A 240 minutes Correct Answer Incorrect Answer
    B 180 minutes Correct Answer Incorrect Answer
    C 300 minutes Correct Answer Incorrect Answer
    D 420 minutes Correct Answer Incorrect Answer
    E 150 minutes Correct Answer Incorrect Answer

    Solution

    According to Question;  Efficiency of pipe ‘A’ = (210/21) = 10 litres/hour  Efficiency of pipe ‘C’ = 10 ÷ 1.25 = 8 litres/hour  Efficiency of pipe ‘B’ = 8 × 1.5 = 12 litres/hour  Time taken by all the pipes together to fill the tank = {210/(10 + 8 + 12)} = (210/30) = 7 hours  Or, time taken by all three pipes together to fill the tank = 7 × 60 = 420 minutes  

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