Data Sufficiency

BTGModeratorVI wrote: ↑

Tue Mar 31, 2020 5:14 am

If x is an integer, is x odd?

(1) x + 4 is an odd integer.
(2) x/3 is NOT an even integer.

Answer: A
Source: Kaplan

Target question: Is x odd?

Some important rules:
1. ODD + ODD = EVEN
2. ODD + EVEN = ODD
3. EVEN + EVEN = EVEN

Statement 1: x + 4 is an odd integer.
Since 4 is EVEN, we have: x + EVEN = ODD
From rule #2 above, we can see that x must be odd
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: x/3 is NOT an even integer.
There are several values of x that satisfy statement 2. Here are two:
Case a: x = 3. Here, x/3 = 3/3 = 1, and 1 is NOT an even integer. In this case, x IS odd
Case b: x = 4. Here, x/3 = 4/3 = 1.333333...., and 1.333333.... is NOT an even integer. In this case, x is NOT odd
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A

Cheers,
Brent