Wrong Term in the Fibonacci-Sum Style Series: 13, 14, 27, 45, 68, 109, 177 — exactly one term is incorrect. Identify the wrong term and justify your choice by revealing the intended rule (each term should be the sum of the previous two).

Verbal Reasoning Number Series Difficulty: Medium
Choose an option
Answer

Correct Answer: 45

Explanation

Introduction / Context:In many number-series questions, the guiding rule is that each term equals the sum of the two preceding terms (a Fibonacci-like construction). Detecting one violation pinpoints the wrong term.

Given Data / Assumptions:

  • Series as given: 13, 14, 27, 45, 68, 109, 177.
  • Exactly one term is erroneous; the rest must follow a single consistent rule.

Concept / Approach:Test the Fibonacci-sum rule a(n) = a(n-1) + a(n-2). If the rule holds everywhere except at one index, that index is the wrong term.

Step-by-Step Solution:Check 3rd term: 13 + 14 = 27 ✓Check 4th term: 14 + 27 = 41 ≠ 45 → mismatchAssuming the rule is correct, the 4th term should be 41, not 45.Continue with corrected term (41): 27 + 41 = 68 ✓41 + 68 = 109 ✓68 + 109 = 177 ✓

Verification / Alternative check:With only the 4th term corrected to 41, the remainder of the sequence fits the rule perfectly. No other single change yields full consistency.

Why Other Options Are Wrong:

  • 27: equals 13 + 14, hence correct.
  • 68: equals 27 + 41 (with repaired 4th term), hence consistent.
  • 109: equals 41 + 68, hence consistent.
  • 177: equals 68 + 109, hence consistent.

Common Pitfalls:Stopping at the first mismatch and changing the preceding term. The minimal-change strategy is to change the mismatching term itself (45 → 41).

Final Answer:45

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