Seven consecutive numbers — Averages Aptitude Question
Seven consecutive numbers: The average of seven consecutive numbers is 20. What is the largest of them? Answer and worked solution on CodeKairo.
- Topic: Averages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 40 seconds
Question
The average of seven consecutive numbers is 20. What is the largest of them?
Options
- 21
- 22
- 23
- 24
Show the answer and the worked solution
Correct answer: C. 23
Worked solution
- With seven consecutive terms the middle one is the average, so it is 20.
- The numbers are 17, 18, 19, 20, 21, 22, 23.
- The largest is 23.
Answer: 23.
The idea
For an odd count of consecutive numbers, the average is the middle term and the largest is average + (count − 1)/2.
Shortcut. Smallest + largest = 2 × 20 = 40 and they are 6 apart, so the largest is (40 + 6) ÷ 2 = 23.
Common trap. "24" — stepping four places up from the middle term instead of three; the middle is the 4th of seven, so only three terms lie above it.