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    Question

    Working together A and B can do a job in 40 days, B and

    C in 36 days and all three together in 24 days. In how many days can B alone do the job?
    A 60 Correct Answer Incorrect Answer
    B 90 Correct Answer Incorrect Answer
    C 72 Correct Answer Incorrect Answer
    D 120 Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    Given that three people together can do the work in 24 days (1/a)+(1/b)+(1/c)=1/24 Also given (1/b) +(1/c)=1/36 1/a =1/24 - 1/36 1/a =(3-2)/72 a=72 days (1/72)+(1/b)=1/40 (1/b)=(1/40)-(1/72) (1/b)=9-5/360 1/b =1/90 b=90 days

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