Data Sufficiency

BTGmoderatorDC wrote:If p is an integer greater than 1, is p a prime number?

(1) p is a factor of 13
(2) p is a factor of 78

Given: p is an integer greater than 1

Target question: Is p a prime number?

Statement 1: p is a factor of 13
13 has exactly two factors: 1 and 13
Since p > 1, we KNOW that p = 13 (which is prime)
The answer to the target question is YES, p IS prime
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: p is a factor of 78
The factors of 78 are: 1, 2, 3, 6, 13, 26, 39, 78
So, p can have MANY values. Here are two:
Case a: If p = 2, then the answer to the target question is YES, p IS prime
Case b: If p = 6, then the answer to the target question is NO, p is NOT prime
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A

Cheers,
Brent