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    Question

    A can complete a task 40% more efficiently in 25 days,

    whereas B, with a 25% efficiency boost, can finish the same task in 21 days. They collaborated at their original efficiencies for 9 days. Now, how we can determine the time it will take for A to complete the remaining work, reverting to his original efficiency level when working alone.
    A 14 days Correct Answer Incorrect Answer
    B 21 days Correct Answer Incorrect Answer
    C 25 days Correct Answer Incorrect Answer
    D 13 days Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    ATQ, Let total amount of work be 525 units Amount of work done by ‘A’ in one day (with increased efficiency) = 525/25 = 21units Original efficiency of ‘A’ = 21/1.40 = 15 units per day Amount of work done by ‘B’ in one day (with increased efficiency) = 525/21 = 25units Original efficiency of ‘B’ = 25/1.25 = 20 units per day Amount of work completed by ‘A’ and ‘B’ together in 9 days = 35 × 9 = 315 units Remaining work = 525 – 315 = 210 units Desired time = 210/15 = 14 day

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