Classification — pick the odd pair of numbers: identify the single pair that does NOT follow the same pattern as the other three.

Introduction / Context:
Odd-pair classification problems usually hide a simple arithmetic link that three options share while one pair diverges. The quickest checks are fixed differences (e.g., +9), reversals, or parity patterns. Our task is to locate the unique mismatch.

Given Data / Assumptions:

• Pairs: 34:43, 55:62, 62:71, 83:92.
• Assume a consistent transformation from the first to the second number within most pairs.
• Exactly one pair breaks the common rule.

Concept / Approach:
Test the simplest invariant: a constant increment from left to right. Compute right − left for each pair and compare the results.

Step-by-Step Solution:
1) 34 → 43: difference = 9.2) 55 → 62: difference = 7.3) 62 → 71: difference = 9.4) 83 → 92: difference = 9.5) Three pairs increase by +9; only one increases by +7.

Verification / Alternative check:
Try a second lens: digit-pattern stability. In three pairs, adding 9 preserves the tens digit while increasing the ones appropriately (when carry allows); the 55:62 pair does not match the +9 motif, confirming it as the outlier.

Why Other Options Are Wrong:
34:43, 62:71, and 83:92 all obey the uniform +9 increment; they are consistent with the majority rule.

Common Pitfalls:
Overcomplicating with prime checks or reversals. Always test constant differences first in number-pair questions.

Final Answer:
55 : 62