Positions after a swap — Seating & Puzzles Aptitude Question
Positions after a swap: In a row of 40 students, Amit is 11th from the left. If he exchanges places with Sunil, who… Answer and worked solution on CodeKairo.
- Topic: Seating & Puzzles
- Section: Logical Reasoning
- Difficulty: Medium
- Time target: 75 seconds
Question
In a row of 40 students, Amit is 11th from the left. If he exchanges places with Sunil, who is 19th from the right, what is Amit's new position from the left?
Options
- 19th
- 20th
- 21st
- 22nd
Show the answer and the worked solution
Correct answer: D. 22nd
Worked solution
- Sunil's position from the left = 40 − 19 + 1 = 22.
- After the swap Amit takes that seat, so he is 22nd from the left.
Answer: 22nd.
The idea
Convert both positions to the same reference end before comparing. The +1 in the conversion is the step usually missed.
Shortcut. Position from the left = total − position from the right + 1 = 40 − 19 + 1 = 22. Amit's original 11th is a red herring: he simply inherits Sunil's seat.
Common trap. "21st" — computing 40 − 19 and forgetting the +1 when converting Sunil's position to a count from the left.