val1e wrote:Here's my issue:

Let's take, for example, the following problem

If m is an integer, is m odd?

(1) m/2 is not an even integer
(2) m-3 is an even integer

This is quite simple to answer:

(1) If m/2 is not an even integer then it's either not an integer or it's an odd integer so statement 1 is NOT sufficient
(2) If m-3 is even then m must be odd so statement 2 IS sufficient

So the answer is "B) Statement 2 alone is sufficient, but statement 1 is not"

But what if statement (2) would look like this:

(2) m-2 is an even integer

In this case m must be even for obvious reasons. The way I see it is that I have found out that m is NOT odd (the question being 'ís m odd?') but I don't know whether I should mark down the same answer as above (B) or E.

You need to mark it as B. Because you reached a point where the answer is a definite NO.

in DS questions, goal is to reach a definite YES or a definite NO.
Then the stmt is said to be Sufficient.

kvcpk wrote: in DS questions, goal is to reach a definite YES or a definite NO.
Then the stmt is said to be Sufficient.

PERFECT! I like to say that Data Sufficiency is related to DECIDIBILITY and, therefore, to the ability to DECIDE whether something may or may not be inferred by the statement(s) given.

My suggestion: when the problem stem is:

"Is m odd?"

try to remember that the REAL question stem is:

"Is it possible to DECIDE whether m is odd?"

In this sense, when you

> DECIDE that m is even, then you´ve DECIDED about it, therefore it DECIDES!
> DECIDE that m is (say) non-integer, you´ve also DECIDED about the matter.

I usually say you BIFURCATED when you find TWO different answers to the question presented at the question stem, that is, you found (at least) TWO different "paths", both of them satisfying the statement(s) being considered. This is the proper way to GUARANTEE the statement(s) considered do not decide, that is, the info is not enough to answer the question asked.

So... I suggest you use the terms "BIFURCATION" and "DECIDE" to be sure you are looking for the decidibility (or not)...

Regards,
Fábio.