Difficulty: Medium
Correct Answer: 3-4-14
Explanation:
Introduction / Context:
Prime identification within short triples is a common classification trick. Here, the last term is decisive: three are primes; one is composite.
Given Data / Assumptions:
Concept / Approach:
Check whether the final number of each triple is prime. If only one is composite, it is the odd one out.
Step-by-Step Solution:
56–57–67 → 67 is prime.102–103–113 → 113 is prime.22–23–13 → 13 is prime.3–4–14 → 14 is composite (2 * 7).
Verification / Alternative check:
Quick divisibility rules: 14 is even → divisible by 2; the others are not divisible by small primes (3, 5, 7) within their bounds, confirming primality.
Why Other Options Are Wrong:
Common Pitfalls:
Overanalyzing the first two terms. The discriminant here is solely the primality of the third term.
Final Answer:
3-4-14
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