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    Question

    ‘P’ takes 25 days to complete a piece of work. ‘Q’

    is 25% more efficient than ‘P’. Find the time taken by them to complete 90% of the work together.
    A 10 days Correct Answer Incorrect Answer
    B 12 days Correct Answer Incorrect Answer
    C 15 days Correct Answer Incorrect Answer
    D 5 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the total work be 100x units.
    Efficiency of P = 100x / 25 = 4x units/day.
    Q is 25% more efficient than P.
    So, Q's efficiency = 4x + (25% of 4x) = 4x + x = 5x units/day.
    90% of work = 100x × 0.90 = 90x units.
    Combined efficiency (P + Q) = 4x + 5x = 9x units/day.
    Time taken = 90x / 9x = 10 days.

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