Position from both ends — Aptitude Question
Position from both ends: In a row of students, Ravi is 12th from the left and 18th from the right. Answer and worked solution on CodeKairo.
- Topic: Seating & Puzzles
- Section: Logical Reasoning
- Difficulty: Easy
- Time target: 45 seconds
Question
In a row of students, Ravi is 12th from the left and 18th from the right. How many students are there in the row?
Options
- 28
- 29
- 30
- 31
Show the answer and the worked solution
Correct answer: B. 29
Worked solution
- Total = 12 + 18 − 1 = 29.
- The subtraction removes the double count of Ravi himself.
Answer: 29.
The idea
Position from left + position from right − 1 = total. Forgetting the −1 gives 30, which is offered.
Shortcut. Ravi has 11 people on his left and 17 on his right: 11 + 17 + 1 = 29.
Common trap. "30" — adding 12 and 18, which counts Ravi twice.