Question

    ‘X’ can complete a job in 30 days. ‘Y’ is 50%

    more efficient than ‘X’. How long will they take to finish 75% of the work together?
    A 10 days Correct Answer Incorrect Answer
    B 12 days Correct Answer Incorrect Answer
    C 6 days Correct Answer Incorrect Answer
    D 9 days Correct Answer Incorrect Answer

    Solution

    Let work = 30x units (since X takes 30 days).
    Efficiency of X = 30x / 30 = 1x unit/day.
    Y is 50% more efficient, so Y's efficiency = 1x + 0.5x = 1.5x units/day.
    75% of work = 30x × 0.75 = 22.5x units.
    Combined efficiency = 1x + 1.5x = 2.5x units/day.
    Time taken = 22.5x / 2.5x = 9 days.

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