Difficulty: Easy
Correct Answer: 4-32
Explanation:
Introduction / Context:Numeric classification often uses exponent relations, such as squares and cubes. In this set, the intended relation is second = first^3. Identifying the pair that breaks this rule requires quick recognition of small powers and comfort with mental arithmetic under time pressure.
Given Data / Assumptions:
Concept / Approach:Compute cubes of 2, 3, 4, and 5. Compare against the second number of each pair. Any mismatch identifies the odd pair. This is a straightforward recognition task that benefits from memorizing cubes up to at least 10 for speed.
Step-by-Step Solution:
2-8 → 2^3 = 8 (fits).3-27 → 3^3 = 27 (fits).4-32 → 4^3 = 64 (does not match 32; 32 equals 2^5).5-125 → 5^3 = 125 (fits).Verification / Alternative check:Note that 32 is a power of 2 (2^5), which can distract solvers who lean on recognition of common powers without checking the base. Confirm by direct multiplication for 4^3: 4*4*4 = 16*4 = 64.
Why Other Options Are Wrong:
2-8 follows the cube rule.3-27 follows the cube rule.5-125 follows the cube rule.Common Pitfalls:Confusing powers of 2 with cubes of other integers. Always compute the exact power relation defined by the pattern rather than relying on familiarity with a single number like 32.
Final Answer:4-32
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