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    Question

    Working 2 hours per day, R1 alone can complete a work

    in 6 days. Working 5 hours per day, R2 alone can complete the same work in 4 days. Working 3 hours per day, in how many days both R1 and R2 together can complete the same work?
    A 5 days Correct Answer Incorrect Answer
    B 2.5 days Correct Answer Incorrect Answer
    C 7 days Correct Answer Incorrect Answer
    D 3.5 days Correct Answer Incorrect Answer

    Solution

    Total hours are taken by R1 = 2 x 6 = 12 hours Total hours taken by R2 = 5 x 4 = 20 hours Let, m = time taken in hours by R1 and R2 ⇒ 1/12 + 1/20 = 1/m 8m = 60 m = 60/8 hours Time taken in days if R1 and R2 works 3 hours a day = 60/(8  x 3) = 60/24 = 2.5 days

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