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8th Class Mathematics Direct and Inverse Proportions Question Bank Direct & Inverse Proportional (Time & Work)

  • question_answer
    A is thrice as good a work man as B and therefore is able to finish a job in 60 days less than B, working together they can do it in:

    A)  20 days           

    B)  \[22\frac{1}{2}\] days      

    C)  25 days                       

    D)  30 days

    Correct Answer: B

    Solution :

    (b): A can do work in x days. B can do work in 3x days. \[\therefore 3x-x=60\] \[x=30.\] Together time \[=\frac{1}{\frac{1}{x}+\frac{1}{3x}}=\frac{3x}{4}\] \[=\frac{3\times 30}{4}=\frac{90}{4}=22\frac{1}{2}\] days.


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