QUESTION

CSAT

Hard

Maths

Prelims 2022

Consider the following statements in respect of two natural numbers p and q such that p is a prime number and q is a composite number:

  1. p×qp \times q can be an odd number.
  2. q/pq / p can be a prime number.
  3. p+qp + q can be a prime number.

Which of the above statements are correct?

Select an option to attempt

Explanation

p is a prime number. So, pp can be 22, 33, 55, 77, 1111, 1313, etc. q is a composite number. So, qq can be 44, 66, 88, 99, 1010, etc.

Statement 1: p×qp \times q can be an odd number. For example, let p=3p = 3 (prime) and q=9q = 9 (composite). p×q=3×9=27p \times q = 3 \times 9 = 27, which is an odd number. Hence, statement 1 is correct.

Statement 2: q/pq / p can be a prime number. For example, let p=2p = 2 (prime) and q=4q = 4 (composite). q/p=4/2=2q / p = 4 / 2 = 2, which is a prime number. Hence, statement 2 is correct.

Statement 3: p+qp + q can be a prime number. For example, let p=3p = 3 (prime) and q=4q = 4 (composite). p+q=3+4=7p + q = 3 + 4 = 7, which is a prime number. Hence, statement 3 is correct.

Since all three statements hold true in at least one case, all the statements 1, 2, and 3 are correct.

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