Difficulty: Easy
Correct Answer: 197
Explanation:
Introduction / Context:
When first differences are not constant but still show a simple structure, the second-level pattern (how the differences change) often reveals the rule.
Given Data / Assumptions:
Concept / Approach:
Compute consecutive differences and look for a linear pattern (e.g., +k, +2k, +3k, …). Then extend that pattern to project the next main term.
Step-by-Step Solution:
Differences: 15−2 = 13; 41−15 = 26; 80−41 = 39; 132−80 = 52.These are 13, 26, 39, 52 = 1*13, 2*13, 3*13, 4*13.Next difference = 5*13 = 65.Next term = 132 + 65 = 197.
Verification / Alternative check:
The sequence can be reconstructed from 2 by repeatedly adding 13n for n = 1,2,3,4,5…, which unambiguously yields 197 next.
Why Other Options Are Wrong:
150, 178, 180 are not 65 more than 132; adopting them would break the clear multiples-of-13 pattern.
Common Pitfalls:
Assuming a geometric ratio or adding a fixed number, missing the structured increment growth (second-level linearity).
Final Answer:
197
Discussion & Comments