Is the integer \(k\) a prime number?

[VJesus12]

Is the integer \(k\) a prime number?

(1) \(2k = 6\)
(2) \(1 < k < 6\)

Answer: A

Source: Official Guide

[Brent@GMATPrepNow]

Is the integer \(k\) a prime number?

(1) \(2k = 6\)
(2) \(1 < k < 6\)

Answer: A

Source: Official Guide

Target question: Is k a prime number?

Given: k is an integer

Statement 1: 2k = 6
Solve to get: k = 3
3 is a prime number, so the answer to the target question is YES, k IS a prime number
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: 1 < k < 6
There are several values of k that satisfy statement 2. Here are two:
Case a: k COULD equal 2, in which case, the answer to the target question is YES, k IS a prime number
Case b: k COULD equal 4, in which case, the answer to the target question is NO, k is NOT a prime number
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A

Cheers,
Brent