Question

    A and B can do job in 6 days. B and C can do same job in

    12 days. A, B and C together can do same job in 4 days. In how many days A and C together can complete the job?
    A 5 days Correct Answer Incorrect Answer
    B 4 days Correct Answer Incorrect Answer
    C 4.5 days Correct Answer Incorrect Answer
    D 3 days Correct Answer Incorrect Answer

    Solution

    Total work = Number of days×1 day’s work (efficiency) Total work = LCM (6, 12, 4) = 12 unit 1 day’s work of (A+B) = 12/6 = 2 unit 1 day’s work of (B + C) = 12/12 = 1 unit 1 day’s work of (A + B + C) = 12/4 = 3 unit Now, 1 day’s work of A = 3 – 1 = 2 1 day’s work of C = 3 – 2 = 1 1 day’s work of A and C = 2 + 1 = 3 A and C together can complete the job in = 12/3 = 4 days

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