Wrong Term in a Halving-Difference Series: 36, 20, 12, 8, 6, 5.5, 4.5 — find the single term that breaks the “subtract half the previous difference” rule.

Introduction / Context:
Some decreasing series are produced by repeatedly halving the previous step’s subtraction. We look for one term that violates that precise halving cadence.

Given Data / Assumptions:

• Given terms: 36, 20, 12, 8, 6, 5.5, 4.5.
• Expected differences should follow: −16, −8, −4, −2, −1, −0.5, …

Concept / Approach:
Compute actual step differences and compare to the “each difference halves” template.

Step-by-Step Solution:
36 → 20: −16 (OK)20 → 12: −8 (OK)12 → 8: −4 (OK)8 → 6: −2 (OK)6 → 5.5: −0.5 (should be −1) → mismatchIf corrected to 6 → 5: −1, then 5 → 4.5: −0.5 fits the halving rule.

Verification / Alternative check:
The only inconsistent step is at 6 → 5.5; replacing 5.5 with 5 restores perfect halving.

Why Other Options Are Wrong:

• 20, 12, 6, 4.5: each sits exactly on the halving path once 5.5 is corrected to 5.0.

Common Pitfalls:
Assuming the last two steps are both flexible; the halving rule fixes them uniquely.

Final Answer:
5.5