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    Question

    ‘A’ and ‘B’ can do a piece of work in 20 days

    and 25 days, respectively. They started working together but ‘A’ left after 4 days. Find the time taken by ‘B’ to complete the remaining work.
    A 10 days Correct Answer Incorrect Answer
    B 12 days Correct Answer Incorrect Answer
    C 16 days Correct Answer Incorrect Answer
    D 15 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let total amount of work be 100 units (LCM of 20 and 25). Efficiency of ‘A’ = 100/20 = 5 units/day Efficiency of ‘B’ = 100/25 = 4 units/day Amount of work done by ‘A’ and ‘B’ together in 4 days = (5 + 4) × 4 = 36 units Time taken by B to complete remaining work = {(100 – 36)/4} = 16 days

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