Question

    A and B together can complete a piece of

    work in 40 days while B and C together can complete the same work in 55 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 52 days Correct Answer Incorrect Answer
    B 57 days Correct Answer Incorrect Answer
    C 50 days Correct Answer Incorrect Answer
    D 55 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 = 1320 (LCM of 40, 55 and 33)
    Efficiency of (A + B) = 1320/40 = 33 units per day
    Efficiency of (B + C) = 1320/55 = 24 units per day
    Efficiency of (A + B + C) = 1320/33 = 40 units per day
    Efficiency of A = 40 – 24 = 16 units per day
    Efficiency of C = 40 – 33 = 7 units per day
    Desired time = 1320/23 = 57.4 days = 57 days

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