Question

    A and B together can complete a piece of

    work in 35 days while B and C together can complete the same work in 42 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 122 days Correct Answer Incorrect Answer
    B 157 days Correct Answer Incorrect Answer
    C 50 days Correct Answer Incorrect Answer
    D 142 days Correct Answer Incorrect Answer
    E 160 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 = 2310 (LCM of 35, 42 and 33)
    Efficiency of (A + B) = 2310/35 = 66 units per day
    Efficiency of (B + C) = 2310/42 = 55 units per day
    Efficiency of (A + B + C) = 2310/33 = 70 units per day
    Efficiency of C = 70 – 66 = 15 units per day
    Efficiency of A = 70 – 55 = 4 units per day
    Desired time = 2310/19 = 121.6 days = 122 days

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