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Railways PYQCBT 2 2017

RRB NTPC · Question 23

P is 4 times faster than Q in doing a job. Q takes 27 more days than P to finish the job. If they work together, in how many days will the work be finished?

  1. \(6 \dfrac{4}{5} \rm \ days\)

  2. \(7 \dfrac{2}{5} \rm \ days\)

  3. \(7 \dfrac{3}{5} \rm \ days\)

  4. \(7 \dfrac{1}{5} \rm \ days\)

Show answer & explanation

Answer: (D) \(7 \dfrac{1}{5} \rm \ days\)

Explanation

If P takes t days, Q takes 4t, and 4t − t = 27 gives t = 9. So P takes 9 and Q 36 days. Together: 1/9 + 1/36 = 5/36 per day, so 36/5 = 7 1/5 days.