X is a collection of certain odd numbers whereas Y is a collection of certain even numbers. T consists of the numbers all of whic…
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.
X is a collection of certain odd numbers whereas Y is a collection of certain even numbers. T consists of the numbers all of which are either from X or from Y. Is every number of T from Y?
Statement I: The sum of any two numbers belonging to T is even.
Statement II: If both p and q are picked from T, then (p − 1)q is even.
- A. The question can be answered using one of the statements alone, but cannot be answered using the other statement alone.
- 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)
Correct Answer
Option D — The question cannot be answered even using both the statements together.
Detailed Solution & Explanation
The correct answer is Option D (cannot be answered even together).
Key Points
- T is drawn entirely from the odd set X or the even set Y.
- Statement I (sum of any two in T is even) forces all elements of T to share the same parity — but that could be all-odd (from X) or all-even (from Y).
- Statement II ((p−1)q even for any p, q) likewise only guarantees a single parity for T, not which one.
Additional Information
- Both statements are consistent with T being entirely odd (answer No) or entirely even (answer Yes), so even together they cannot decide — Option D.