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CAT 2003 Slot 2 — QA Question 7

Prime and Composite NumbersEasy

Let x and y be positive integers such that x is prime and y is composite. Then,

Answer & solution

  • A

    (y – x) cannot be an even integer.

  • B

    xy cannot be an even integer.

  • C

    (x + y)/x cannot be an even integer.

  • None of these

Solution

Option 1: False

∵ (y – x) is equal to an even integer when x = 2 and y = 6

Option 2: False

∵ xy is an even integer whenever x = 2 and y = 6

Option 3: False

∵ (x + y)/x is an even integer when x = 3 and y = 6, 9, 15, 21, 27… and so on. (i.e. Taking any value of x and then taking y as a multiple of that x will work.)

Hence, option (d).

CAT 2003 Slot 2 QA Q7: Let x and y be positive integers such that x is prime and y is composite. Then, — Solution | TheCATExam