If x, y and z are integers, each greater than 1, then is x a prime number?
Mental Ability & Logical Reasoning ·Previously asked in UPSC Civil Services Examination 2026
View the full solved paper: GS Paper II
Question
Directions: The question is followed by two statements. Answer using the codes given in the options.
If x, y and z are integers, each greater than 1, then is x a prime number?
Statement I: xy² = 116
Statement II: xz = 261
- A. The question can be answered using one of the statements alone, but cannot be answered using the other statement alone. (Correct answer)
- B. The question can be answered using either statement alone.
- C. The question can be answered using both the statements together, but cannot be answered using either statement alone.
- D. The question cannot be answered even using both the statements together.
Correct Answer
Option A — The question can be answered using one of the statements alone, but cannot be answered using the other statement alone.
Detailed Solution & Explanation
The correct answer is Option A (one statement alone suffices).
Key Points
- Statement I (xy² = 116): since 116 = 2² × 29 and y > 1, the only square factor is 4, giving y = 2 and x = 29, which is prime — a definite "Yes". Sufficient.
- Statement II (xz = 261): 261 = 3² × 29, so x could be 3, 9, 29 or 87 — a mix of prime (3, 29) and non-prime (9, 87). Insufficient.
Additional Information
- Statement I settles it and Statement II does not, so the answer is Option A.