Difficulty: Easy
Correct Answer: (105, 125, 145)
Explanation:
Introduction / Context:
The given set (15, 27, 39) forms an arithmetic progression with common difference 12. We need a choice set that also exhibits a constant common difference (not necessarily the same value), preserving the “AP structure.”
Given Data / Assumptions:
Concept / Approach:
Scan options for a trio with identical successive differences.
Step-by-Step Solution:
1) (105, 125, 145): +20, +20 → constant difference.2) Other options either mix values or fail to maintain equal gaps.
Verification / Alternative check:
Arithmetic progressions require d(n+1 − n) to be equal for each step; only option (105, 125, 145) satisfies this strictly.
Why Other Options Are Wrong:
They lack a consistent common difference across both gaps.
Common Pitfalls:
Choosing sets that look “roughly increasing” but are not true APs.
Final Answer:
(105, 125, 145)
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