A new observation is added — Averages Aptitude Question
A new observation is added: The average of 6 observations is 12. A new observation is included and the average… Answer and worked solution on CodeKairo.
- Topic: Averages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
The average of 6 observations is 12. A new observation is included and the average becomes 13. What is the new observation?
Options
- 13
- 16
- 19
- 22
Show the answer and the worked solution
Correct answer: C. 19
Worked solution
- Old total = 72; new total = 7 × 13 = 91.
- New observation = 91 − 72 = 19.
Answer: 19.
The idea
New value = new average + old count × rise = 13 + 6 × 1 = 19. The same relation as the batsman questions, in smaller numbers.
Shortcut. New observation = old average + new count × rise = 12 + 7 × 1 = 19.
Common trap. "13" — taking the new observation to be the new average; adding 13 lifts the average only to 85 ÷ 7 ≈ 12.1.