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    Question

    A and B can complete a task together in 14 days, while B

    alone takes 28 days to finish it. A began working alone and left after ‘x’ days, after which B completed the remaining work in 21 days. Determine the percentage of the total work completed by A.
    A 25% Correct Answer Incorrect Answer
    B 15% Correct Answer Incorrect Answer
    C 20% Correct Answer Incorrect Answer
    D 40% Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let total amount of work be 28 units
    Efficiency of (A + B) = 28/14 = 2 units/day
    Efficiency of ‘B’ = 28/28 = 1 unit/day
    Amount of work done by ‘B’ = 21 × 1 = 21 units
    Percentage of work done by ‘A’ = {(28 – 21)/28} × 100 = 25%

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