A lift has the capacity of 18 adults or 30 children. How many children can board the lift with 12 adults?
Answer & explanation
Answer: (b) 10
18 adults take the same space as 30 children, so one adult equals 5/3 of a child. 12 adults use the space of 20 children, leaving room for 10.
- 18 adults = 30 children, so 1 adult = 30/18 = 5/3 children.
- 12 adults = 12 × 5/3 = 20 children's worth of space.
- Room left = 30 − 20 = 10 children.
- Check: 12 adults fill 12/18 = 2/3 of the lift; the remaining 1/3 of 30 children is 10.
Remember · Convert everything to one unit (here child-spaces), subtract what is used, and read off what remains.
Question and answer: UPSC's official GS Paper II (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·