RRB NTPC · Question 99
X, Y and Z can do a piece of work in 30 days, 45 days and 90 days respectively. In how many days can the work be completed if X is assisted by Y and Z together, on every second day?
Show answer & explanation
Answer: (B) 20 days
Explanation
X does 1/30 a day; Y and Z together do 1/45 + 1/90 = 1/30. In every 2 days X works twice and Y + Z once: 3/30 = 1/10 of the work. The whole work takes 20 days.