New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    Jack is twice efficient as Jill and Jill can do a piece

    of work in 30 days. Jill started the work and after a few days Jack joined him. They completed the work in 22 days. From the starting, for how many days they worked together?
    A 6 days Correct Answer Incorrect Answer
    B 8 days Correct Answer Incorrect Answer
    C 4 days Correct Answer Incorrect Answer
    D 10 days Correct Answer Incorrect Answer

    Solution

    Jill Jack Efficiency 1 : 2 Jill can do this job in 30 days so let total work = 1×30 = 30 units So let Jill work alone for x days and they work together for remaining i,e. (22-x) Hence 1×x+3(22-x) = 30 x +66 - 3x = 30 36 = 2x So x = 18 days So they work togethr for (22-x) i.e . 4 days

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