Question

    A and B together can complete a piece of

    work in 55 days while B and C together can complete the same work in 66 days. All of three together can complete 80% of the whole work in 26.4 days then find the time taken by A and C together to complete the whole work. Note: You have to find approx. value
    A 22 days Correct Answer Incorrect Answer
    B 28 days Correct Answer Incorrect Answer
    C 39 days Correct Answer Incorrect Answer
    D 37 days Correct Answer Incorrect Answer
    E 60 days Correct Answer Incorrect Answer

    Solution

    Time taken by A, B and C together to complete the whole work = 26.4/0.80 = 33 days
    Let total amount of work = 330 (LCM of 55, 66 and 33)
    Efficiency of (A + B) = 330/55 = 6 units per day
    Efficiency of (B + C) = 330/66 = 5 units per day
    Efficiency of (A + B + C) = 330/33 = 10 units per day
    Efficiency of A = 10 – 5 = 5 units per day
    Efficiency of C = 10 – 6 = 4 units per day
    Desired time = 330/9 = 36.6 days = 37 days

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