BTGModeratorVI wrote: ↑

Tue Jul 07, 2020 6:28 am

If a, b, and c are consecutive integers, such that a < b < c, is their sum even?

(1) abc = 0
(2) a + c = 0

Answer: B
Source: Kaplan

Given: a, b, and c are consecutive integer, such that a < b < c

Target question: Is a + b + c EVEN?

Statement 1: abc = 0
This tells us that a = 0, b = 0 or c = 0
Here are two possible cases:
Case a: a = 0, b = 1 and c = 2. In this case, a + b + c = 0 + 1 + 2 = 3 (odd). So, the answer to the target question is NO, a + b + c is NOT even
Case b: a = -1, b = 0 and c = 1. In this case, a + b + c = -1 + 0 +1 = 0 (even). So, the answer to the target question is YES, a + b + c IS even
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: a + c = 0
We already know that a, b, and c are consecutive integers, AND a < b < c
So, if a + c = 0, we can be certain that a = -1, b = 0 and c = 1
In this case, a + b + c = -1 + 0 + 1 = 0 (even). So, the answer to the target question is YES, a + b + c IS even
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent