Practice Test Discussion


'A' alone can do a certain job in 15 days while B alone can do it in 10 days. 'A' started the work and was joined by B after 5 days. For how long did this work last?

  • Explanation

    According to the question,

    In 5 days A can complete=115×5=13rd of the work

    Remaining work =1-13=23

    In one day (A+B) can complete=115+110=2+330=530=16th of the work

    ∴ 23 rd of the work will be finished by (A+B) in 23×6 days that is in 4 days.

    ∴ Total time taken= (5+4) days =9 days.

     Hence option D is the correct.

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