Prelims 2026 · CSAT / Quantitative Aptitude · Question 4
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?<br/>Statement I :<br/>The sum of any two numbers belonging to T is even.<br/>Statement II :<br/>If both p and q are picked from T, then (p - 1)q is even.<br/>
Answer
Select this option if the question cannot be answered even using any of the statements
We need to know whether all numbers in T are even.
Statement I: sum of any two numbers in T is even. So T cannot contain one odd and one even together; all members have same parity. Could be all even or all odd. Not sufficient.
Statement II: for any p,q in T, (p−1)q is even. If any odd q is chosen, then p−1 must be even for every p, so all p are odd. If all q are even, then all members are even. Again T is forced to be all odd or all even. Not sufficient.
Together still do not tell whether T is all even or all odd.