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    Question

    A man can complete a job alone in 20 days. A woman can

    complete half of the same job in 15 days. If both work together, how many days will it take them to complete 80% of the job?
    A 15.5 days Correct Answer Incorrect Answer
    B 17.2 days Correct Answer Incorrect Answer
    C 14.5 days Correct Answer Incorrect Answer
    D 9.6 days Correct Answer Incorrect Answer

    Solution

    ATQ,

    Time taken by the woman to finish the entire work = 15 ÷ 0.5 = 30 days

    Let the total work be 60 units. {LCM of (20 and 30)}

    So, efficiency of the man = 60 ÷ 20 = 3 units/day

    And efficiency of the woman = 60 ÷ 30 = 2 units/day

    So, required time = (60 × 0.8) ÷ (3 + 2) = 9.6 days

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