AS # 43

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Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Sun Oct 25, 2015 2:59 pm
oquiella wrote:43. If M, N, and P are integers, is (M+N+P) even?


(1) MNP is even
(2) M+N = P
Target question: Is (M+N+P) even?

Given: M, N, and P are integers

Statement 1: MNP is even
From this information, we can conclude that AT LEAST 1 of the 3 values is EVEN.
There are several values of M, N and P that satisfy statement 1. Here are two:
Case a: M = 1, N = 1, and P = 2, M + N + P = 1 + 1 + 2 = 4, which is EVEN
Case b: M = 1, N = 2, and P = 2, M + N + P = 1 + 2 + 2 = 5, which is NOT EVEN
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: M + N = P
If M + N = P, then M + N + P = P + P = 2P which is EVEN
So, it MUST be the case that M + N + P is even
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer = B

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Brent
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by Matt@VeritasPrep » Sun Oct 25, 2015 11:16 pm
S1::

MNP = even, so at least one of M, N, and P is even.

But we could have 2*3*4 or 2*3*5; NOT SUFFICIENT.

S2::

M + N = P

So M + N + P is really P + P, or 2P, which must be even. SUFFICIENT!