In each of the following number series only one number is wrong. Find out the…
2024
In each of the following number series only one number is wrong. Find out the wrong number.
10, 5, 19, 12, 39, 26, 73, 54
- A.
5
- B.
19
- C.
39
- D.
26
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Show answer & explanation
Correct answer: C
Key insight: the given series splits into two interleaved subsequences (terms in odd positions and terms in even positions). Each subsequence follows a pattern where the increments double each step.
Odd-position subsequence (positions 1, 3, 5, 7): 10, 19, 37, 73. Differences: +9, +18, +36 (each difference doubles).
Even-position subsequence (positions 2, 4, 6, 8): 5, 12, 26, 54. Differences: +7, +14, +28 (each difference doubles).
Check the given full series: 10, 5, 19, 12, 39, 26, 73, 54. The odd subsequence as given is 10, 19, 39, 73; 39 does not fit the doubling-increment pattern (it should be 37).
Conclusion: 39 is the incorrect number and should be 37 to maintain the pattern.