Data Sufficiency

I know that this question is already exist in 2010 solving but I have an other question to solving this problem.

111. If x and y are integers, is xy even?

(1) x = y+1
(2) x/y is an even integer.

As you already know that ..
(1) if y is odd, x is even and if y is even, x is odd
so, correct.
(2) x/y = even, x = even * y, so x is always even and xy is even too.

in (2),
if y is 0, x/y have no value (I learnd any kind of number can not devide by '0')
so x/y neither even nor odd isn't it??

the OG result is D.

please reply you opinions on here..

Thanks Brent,

It's my second time posting question, so have less knowledge using board.
I'll use spoiler in next time.

return to the question,
as you said that I understand why the answer is D.

But in DS question, we should decide that the condition is true or false,
In first condition, we can answer it always 'even', so answer is 'true'
but in second condition, I can not answer it always 'even' because it can be a even, almost cases, but it can be 'nothing = neither even nor odd'

May I didn't understand about Data sufficient question algorithm?

Castor.kim wrote:
But in DS question, we should decide that the condition is true or false,
In first condition, we can answer it always 'even', so answer is 'true'
but in second condition, I can not answer it always 'even' because it can be a even, almost cases, but it can be 'nothing = neither even nor odd'

May I didn't understand about Data sufficient question algorithm?

Castor.kim,

In Data Sufficiency questions, we determine the sufficiency of the given statements(statements 1 & 2: individual or combined) to answer the given question (Here the question is, Is x*y= Even ?)

Addressing your query relevant to the given question-->

In the given question, lets consider the statement 2 .
Ask yourself , is x*y = Even ? ,provided that x/y is an even integer?
or, Ask yourself, is the statement 2--> "x/y is an even integer" a sufficient condition to answer whether x*y=Even?
As it is already given in the statement 2 that x/y= even integer,therefore y must not be 0, otherwise the given statement would be invalid.isn't it? I mean to say that,we should consider the statements as valid and establish their sufficiency with respect to the question in hand.

So, our task is to see whether the data given in the statement 2 is sufficient to answer [the answer can be either "yes" or "no" . Either of the answers will be sufficient ] the question .
Here this is very much sufficient.So, answer is D.

Hope this helps!

Oops!!
I fully understand it.

Thanks Brent and kalpita123.
I hope that could be a helpful for other people..

what if y=0 and x is 1 ?

Cool Thanks )