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    Question

    A and B together can do a work in 5 days. If A can alone

    do the same work in 15 days, then in how many days B alone will do the same work?
    A 10 days Correct Answer Incorrect Answer
    B 13 days Correct Answer Incorrect Answer
    C 7.5 days Correct Answer Incorrect Answer
    D 12 days Correct Answer Incorrect Answer

    Solution

    Total work = Number of days×1 day’s work (efficiency) Total work = LCM (5, 15) = 15 unit 1 day’s work of (A+B) = 15/5 = 3 unit 1 day’s work of A = 15/15 = 1 unit 1 day’s work of B = 3 - 1 = 2 unit Now, Time taken by B to completed the work = 15/2 = 7.5 days

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