BTGModeratorVI wrote: ↑Tue Jul 07, 2020 6:24 am
If n is a positive integer, is n odd?
(1) 3n is odd.
(2) n + 3 is even.
Answer:
D
Source: Official guide
Given: n is a positive integer
Target question: Is n odd?
Some important rules:
#1. ODD +/- ODD = EVEN
#2. ODD +/- EVEN = ODD
#3. EVEN +/- EVEN = EVEN
#4. (ODD)(ODD) = ODD
#5. (ODD)(EVEN) = EVEN
#6. (EVEN)(EVEN) = EVEN
Statement 1: 3n is odd
Since 3 is ODD, we are told that (ODD)(n) = ODD
From Rule #4 above, we can conclude that n is ODD
The answer to the target question is
YES, n IS odd
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: n + 3 is even
in other words, n + ODD = EVEN
From Rule #1 above, we can conclude that n is ODD
The answer to the target question is
YES, n IS odd
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
