Find the wrong number in the series given below: 3, 8, 13, 21, 31, 43
2023
Find the wrong number in the series given below:
3, 8, 13, 21, 31, 43
Answer: C. 8 — ConceptIn a number series, inspect the first differences between consecutive terms. A regular arithmetic pattern can be identified when those differences…
- A.
21
- B.
31
- C.
8
- D.
More than one of the above
- E.
None of the above
Attempted by 13 students.
Show answer & explanation
Correct answer: C
Concept
In a number series, inspect the first differences between consecutive terms. A regular arithmetic pattern can be identified when those differences themselves follow a simple sequence.
Application
Test the rule in which consecutive differences are the even numbers +4, +6, +8, +10, and +12.
Starting from 3, adding 4 gives 7, not 8.
Continuing from 7, adding 6, 8, 10, and 12 gives 13, 21, 31, and 43 respectively.
Cross-check and result
The corrected series 3, 7, 13, 21, 31, 43 has successive differences 4, 6, 8, 10, 12. Therefore, the wrong term in the displayed series is 8.