If p is an even integer and q is an odd integer, which of the following must be an odd integer?

A. p/q
B. pq
C. 2p+q
D. 2(p+q)
E. 3p/q
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this is a must question:

A. p/q
can be a non-integer

B. pq
always even

C. 2p+q
2p = even -> even+odd = odd

D. 2(p+q)
always even - p+q = odd *2 -> even

E. 3p/q
might be a non integer.

C

Hi All,

If you know the Number Properties involved in this question, then you can get to the correct answer relatively easily. You can also TEST VALUES to get to the answer.

We're told that P is an EVEN integer and Q is an ODD integer. We're asked which of the following must be an ODD integer...

IF....
P = 2 AND Q = 1, then...

Answer A: 2/1 = 2 NOT an odd
Answer B: 2(1) = 2 NOT an odd
Answer C: 2(2) + 1 = 5 This IS an odd
Answer D: 2(2+1) = 6 NOT an odd
Answer E: 3(2)/1 = 6 NOT an odd

Final Answer:

GMAT assassins aren't born, they're made,
Rich
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Another approach is to take each answer choice and plug in an even number for p and an odd number for q, and see which answer choices yield an ODD value.
The easiest numbers to test are p = 0 (which is EVEN) and q = 1 (which is ODD)

We get:
A. p/q = 0/1 = 0, which is EVEN. ELIMINATE A
B. pq = (0)(1) = 0, which is EVEN. ELIMINATE B
C. 2p+q = 2(0) + 1 = 1, which is ODD. KEEP C
D. 2(p+q) = 2(0 + 1) = 2, which is EVEN. ELIMINATE D
E. 3p/q = (3)(0)/1 = 0, which is EVEN. ELIMINATE E

Answer: C

Cheers,
Brent
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