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    Question

    60 boys can complete a piece of work in 60 days. They

    started the work together. But at the end of every 10th day five more boys have joined. Exactly on which day will the whole work be completed?
    A (50)nd days Correct Answer Incorrect Answer
    B (42)nd days Correct Answer Incorrect Answer
    C (22)nd days Correct Answer Incorrect Answer
    D (52)nd days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ, Required boys -hrs = 60 × 60 = 3600 boys-hrs.  Boys-hrs completed in fifty(50) days  = 10(60 + 65 + 70 + 75 + 80) = 3,500.  Hence Balance left = 3600-3500 = 100 Let X days be required to complete the remaining 100 boys- hrs. Now, (x)(85) = 100 x = 1(3/17) days  i.e., work is completed in 51(3/17) days  i.e., on 52 nd day work is completed.

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