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SSC Sample Paper SSC CHSL (10+2) Sample Test Paper-4

  • question_answer
    A and B can do a piece of work in 20 days and 12 days respectively. A started the work alone and then after 4 days B joined him till the completion of the work. How long did the work last?

    A) 10 days                          

    B)  20 days

    C)  15 days           

    D)         6 days

    Correct Answer: A

    Solution :

     A's 1 day's work\[=\frac{1}{20}\] A's 4 days work\[=\frac{4}{20}=\frac{1}{5}\] Remaining work\[=1-\frac{1}{5}=\frac{4}{5}\] This part is completed by A and B together. Now, (A + B)?s 1 day's work             \[=\frac{1}{20}+\frac{1}{12}\]             \[=\frac{3+5}{60}=\frac{8}{60}=\frac{2}{15}\] Now, \[\frac{2}{15}\]work is done by (A + B) in 1 day. \[\therefore \]\[\frac{4}{5}\]work is done in             \[=\frac{15}{2}\times \frac{4}{5}=6\]days. Hence, the work lasted for\[4+6=10\]days.


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