CA Foundation · Quantitative Aptitude · Number Series, Coding-Decoding and Odd Man Out
In the series 2, 3, 5, 9, 17, 34, 65, one term does not fit the pattern where the difference doubles each time. Which term is wrong?
The wrong term is 34. The differences between terms should double each time (1, 2, 4, 8, 16, 32), so the sequence should be 2, 3, 5, 9, 17, 33, 65. The term 33 is replaced by 34 in the question.
- A9
- B17
- C34Correct
- D65
Explanation
Differences should be 1, 2, 4, 8, 16, 32, giving 2, 3, 5, 9, 17, 33, 65. The given sixth term is 34 instead of 33. Then 33+32=65 matches the last term, so only 34 is wrong. Term 17 is right since 9+8=17.
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