Average of the first 50 natural numbers — Aptitude Question
Average of the first 50 natural numbers: What is the average of the first 50 natural numbers? Answer and worked solution on CodeKairo.
- Topic: Averages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 30 seconds
Question
What is the average of the first 50 natural numbers?
Options
- 25
- 25.5
- 26
- 26.5
Show the answer and the worked solution
Correct answer: B. 25.5
Worked solution
- The numbers 1 to 50 are evenly spaced.
- Average = (1 + 50)/2 = 25.5.
Answer: 25.5.
The idea
Average of 1 to n is (n + 1)/2. Average of the first n even numbers is n + 1; of the first n odd numbers, n.
Shortcut. Pair 1 with 50, 2 with 49 and so on: all 25 pairs total 51, so every pair averages 25.5.
Common trap. 25 — taking half of 50 rather than the midpoint of 1 and 50.