Civil Services Examination · Question 59
X can complete one-third of a certain work in 6 days, Y can complete one-third of the same work in 8 days and Z can complete three-fourth of the same work in 12 days. All of them work together for n days and then X and Z quit and Y alone finishes the remaining work in 8 2/3 days. What is n equal to?
Show answer & explanation
Answer: (B) 4
Explanation
X takes 18 days, Y 24 and Z 16. Y's 26/3 days do 13/36 of the work, so together they did 23/36. Their combined rate is 23/144 per day, so n = 4. (Answer as per the official UPSC answer key.)