When a runner was crossing the 12 km mark, she was informed that she had completed only 80% of the race. How many kilometres was the runner supposed to run in this event?
Answer & explanation
Answer: (b) 15
12 km is four-fifths of the race, so the full distance is 12 × 5/4 = 15 km.
- 12 km = 80% of the race.
- Race = 12 × 100/80 = 15 km.
- Check: 80% of 15 = 12.
Remember · If x is p% of the whole, the whole is x × 100/p.
Question and answer: UPSC's official GS Paper II (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·