Question

    A and B together can complete a piece of work in 30 days while A alone can complete 50% of the work in 25 days. Find the time taken by B to complete 80% of the work.

    A 57 days Correct Answer Incorrect Answer
    B 36 days Correct Answer Incorrect Answer
    C 42 days Correct Answer Incorrect Answer
    D 60 days Correct Answer Incorrect Answer

    Solution

    Time taken by A to complete the whole work = 25/0.50 = 50 days
    Let total work = 150 units
    Amount of work done by A and B together in one day = 150/30 = 5 units
    Amount of work done by A alone in one day = 150/50 = 3 units
    Amount of work done by B in one day = 5 – 3 = 2 units
    Desired time = 0.80 × 150/2 = 60 days

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