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    Question

    The efficiency of inlet pipe 'P' is 60% of the

    efficiency of another inlet pipe 'Q'. When both pipes are opened together, they fill a tank in 4 hours. How long will it take for pipe 'Q', operating at 80% of its efficiency, to fill a tank that is 50% larger in capacity than the original tank?
    A 9.6 hrs Correct Answer Incorrect Answer
    B 12 hrs Correct Answer Incorrect Answer
    C 15 hrs Correct Answer Incorrect Answer
    D 8.4 hrs Correct Answer Incorrect Answer
    E 7.2 hrs Correct Answer Incorrect Answer

    Solution

    Let the efficiency of pipe 'Q' be '5a' litres/hour. So, efficiency of 'P' = 0.6 X 5a = '3a' litres/hour Total capacity of given tank = (3a + 5a) X 4 = '32a' litres Capacity of the tank to be filled by pipe 'Q' = 1.5 X 32a = '48a' litres New efficiency of pipe 'Q' = 0.8 X 5a = '4a' litres/hour Required time = (48a/4a) = 12 hours

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