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    Question

    I and J together complete a piece of work in 20 days. If

    I alone can do it in 50 days, how many days will J alone take?
    A 30 days Correct Answer Incorrect Answer
    B 33 days Correct Answer Incorrect Answer
    C 36 days Correct Answer Incorrect Answer
    D 100/3 days Correct Answer Incorrect Answer

    Solution

    Let the total work be 100 units. {LCM (20 and 50)}
    So, combined efficiency of 'I' and 'J' = 100 ÷ 20 = 5 units/day
    Efficiency of 'I' = 100 ÷ 50 = 2 units/day
    So, efficiency of 'J' = 5 - 2 = 3 units/day
    So, time taken by 'J' to do the work alone = 100 ÷ 3 = (100/3) days

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