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Railways PYQCBT 1 2016

RRB NTPC · Question 17

Anil can do a piece of work in 14 days which Rohit can do in 21 days. They worked together for few days after which Anil left. If Rohit worked alone for 3 days, find the total number of days it took to complete the whole work. A. 31/5 B. 51/5 C. 21/5 D. 13/5

  1. D

  2. B

  3. C

  4. A

Show answer & explanation

Answer: (B) B

Explanation

Anil does 1/14 and Rohit 1/21 of the work a day, together 5/42. Rohit's last 3 days cover 3/21 = 1/7, so the two together did 6/7, taking (6/7) ÷ (5/42) = 36/5 days. Total time = 36/5 + 3 = 51/5 days.