Question

    P and Q can complete a piece of work individually in 12

    days and 20 days, respectively. They start working together, but after 6 days, Q leaves the work. P continues and completes the remaining work alone. How many total days did it take to finish the entire work?
    A 9.6 days Correct Answer Incorrect Answer
    B 7.2 days Correct Answer Incorrect Answer
    C 8.4 days Correct Answer Incorrect Answer
    D 8 days Correct Answer Incorrect Answer

    Solution

    Let total work = 60 units (LCM of 12 and 20)
    Efficiency of 'P' = (60/12) = 5 units/day
    Efficiency of 'Q' = (60/20) = 3 units/day
    Amount of work completed by 'P' and 'Q' together in 6 days = 6 X (5 + 3) = 48 units
    Remaining work = 60 - 48 = 12 units
    Time taken by 'P' to complete the remaining work = (12/5) = 2.4 days
    Required time taken = 6 + 2.4 = 8.4 days

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