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    Question

    A can do a work in 15 days and B in 18 days. If they

    work on it together for 5 days then in how many days the remaining work will be completed by B?
    A 9 days Correct Answer Incorrect Answer
    B 5 days Correct Answer Incorrect Answer
    C 7 days Correct Answer Incorrect Answer
    D 4 days Correct Answer Incorrect Answer

    Solution

    Total work = Number of days×1 day’s work (efficiency) Total work = LCM (15, 18) = 90 unit 1 day’s work of A = 90/15 = 6 unit 1 day’s work of B = 90/18 = 5 unit 1 day’s work of (A + B) = 6 + 5 = 11 unit Now, 5 day’s work of (A + B) together = 5× 11 = 55 unit Remaining work = 90 – 55 = 35 Remaining work completed by B = 35/5 = 7 days

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