if x and y are prime, is xy odd ? 1... x - y is even.

Question

if x and y are prime, is xy odd ?

 1... x − y is even. 
 2... x / y is not an integer. 

 Ο only statement 1 is sufficient to answer the question.
 Ο only statement 2 is sufficient to answer the question.
 Ο neither statement is sufficient, but together, they are.
 Ο statement 1 is very sufficient...and so is statement 2.
 Ο no can do.

hobbit · Answer

C is the answer.

A is not suff. for x=y=2 (st1) holds, and xy is even (for all other options it is indeed odd).

st2 tells us x and y are different.

lfox2 · Answer

if x and y are prime, is xy odd ? 

1... x − y is even. 
2... x / y is not an integer. 

Ο only statement 1 is sufficient to answer the question. 
Ο only statement 2 is sufficient to answer the question. 
Ο neither statement is sufficient, but together, they are. 
Ο statement 1 is very sufficient...and so is statement 2. 
Ο no can do.

1) We know that X and Y are prime and there is only 1 even prime. For X-Y to be even both X and Y must be ODD (Cannot have ODD - EVEN to equal EVEN). This means XY will always be ODD. SUFF

2) Only tells us that Y does not go into X or that X < Y but does not tell us anything that will help in answering this questions.

ANSWER = A

lfox2 · Answer

Yes thinking about it x and y can be 2 since it does not say they are different.

If this is the case, then I would go for C, since statement B tells us that the integers are different.

yezz · Answer

if x and y are prime, is xy odd ? 

1... x − y is even. 
2... x / y is not an integer. 

for xy to be odd thus all we need to proof is x,y not = 2

x-y is even

thus both are odd OR BOTH ARE TWO ........INSUFF

x/y is not an intiger

either ways any prime is not devisible except by itself and one so deviding any two primes will always yield a non integer ( this includes 2 too)...insuff

BOTH TOGETHER 

THEY CANT BE EQUALL THUS MY ANSWER IS C

trivikram · Answer

I will take E

1) say x=5 y=3 product is even though their diff is even
 say x=7 y=3 product is odd though their diff is even
So A not suff

2) x/y not int.

say x=5 y=3 so 5/3 is not an int

so is 7/3 as above

so E should be it

FN · Answer

C it is..we dont know if X and Y are distinct..

ywilfred · Answer

St1:
We know both x and y must be odd primes. So xy is odd. Sufficient.

St2:
Insufficient. 2/7, 3/5 are all non-integers but the first pair (2 and 7) will yield an even product while the second pair (3 and 5) will yield an odd product.

Ans A

FN · Answer

what if x=2 y=2

x-y=0 which is an even number...

2*2=4 which is even...

Priyah · Answer

Fell for this! :wall

EZO · Answer

Should be A....

0 is not an even number.....

yogeshsheth · Answer

O is a even number
answer must be C

WinIT · Answer

OA is C. Thank you all for the explanation.

Matrix02 · Answer

Nice explanation Yezz. 

I fell for that one...

if x and y are prime, is xy odd ? 1... x - y is even.

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards