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    Question

    ‘A’ and ‘B’ can do a piece of work in 15 days

    and 18 days, respectively. They started working together but ‘A’ left after 5 days. Find the time taken by ‘B’ to complete the remaining work.
    A 4 days Correct Answer Incorrect Answer
    B 2 days Correct Answer Incorrect Answer
    C 5 days Correct Answer Incorrect Answer
    D 7 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let total amount of work be 90 units (LCM of 15 and 18). Efficiency of ‘A’ = 90/15 = 6 units/day Efficiency of ‘B’ = 90/18 = 5 units/day Amount of work done by ‘A’ and ‘B’ together in 5 days = (6 + 5) × 5 = 55 units Time taken by B to complete remaining work = {(90 – 55)/5} = 7 days

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