W can do 25% of a work in 30 days, X can do 1/4 of the work in 10 days, Y can do 40% of the work in 40 days and Z can do 1/3 of the work in 13 days. Who will complete the work first?
Answer & explanation
Answer: (d) Z
Scaling each part-job up to the whole work: W needs 120 days, X 40, Y 100 and Z 39. Z finishes first.
- W: 25% in 30 days → 30 ÷ 1/4 = 120 days.
- X: 1/4 in 10 days → 40 days.
- Y: 40% in 40 days → 40 ÷ 2/5 = 100 days.
- Z: 1/3 in 13 days → 39 days — the fastest.
Remember · Convert every rate to days for the whole job (days ÷ fraction done) before comparing.
Question and answer: UPSC's official GS Paper II (2016, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·