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GMAT Data Sufficiency – Yes/No Questions

“Yes/No” questions are a common pattern of GMAT Data Sufficiency problems. In other words, they’re questions where the answer to the question itself will be either “Yes” or “No”. For example:

Is x>0?
(1) …
(2) …

Either x is greater than zero or it’s not. Yes or no.

The objective of “Yes/No” data sufficiency questions is the same as with all GMAT data sufficiency questions: To determine whether or not the given statement(s) is sufficient to answer the question.

The difficulty with these question patterns is that it can be difficult to get your mind around whether or not a statement is sufficient, especially if you’re able to determine from the given statement that the answer to the question would actually be “no.” Yet, the very fact that you were able to determine that the answer to the question would be “no” means that you do in fact have enough information to answer the question. In that case, the statement is question would be sufficient.

To summarize, here’s an important mindset to keep in mind when trying to answer “Yes/No” data sufficiency questions on the GMAT:

Even if a statement leads you to conclude that the answer to the question is “no,” the very fact that you can answer “no” means that you are given enough information to answer the question in the statement. Therefore, the statement is sufficient.

Watch this video to learn more about exactly how to solve “Yes/No” data sufficiency questions:

For your convenience, here is a full transcript of the video above:

0:00
The final pattern is really a pattern that we have touched on with a lot of the other
examples we have done but I want to get very specific about yes/no questions. You will
see a lot of questions on data sufficiency. They are asked in such a way that the answer
to the question itself will be either yes or no and here is the important point. Even
if the statement leads you to conclude that the answer to the question is no the very
fact that you could answer no means that you have been given enough information to answer
the question.
You know it make sense right the very fact that you can answer now means you have been
given enough information and that means that the statement that allowed you to conclude
that is sufficient. Let’s take a look at an example and really hammer home this point.
Here simple straight forward question. Is X greater than 0, yes or no? Is X greater
than 0? Well statement number one says that X2 is greater than 0 so again we chase it
1:00
down the rabbit hole a little bit, we make our lists, what are some possible values of
X and just testing your knowledge about exponents and some rules that will cover during the
exponent lesson in future videos, but nevertheless what is the possible values of X to where
when you cube it the outcome will be less than 0.
Well certainly not something positive right, I mean 22 is positive 32 is positive 1/22
is positive. Anything positive times itself will continue to be positive. Does that make
sense? So it has got to be a negative number. X could be -1 for example because what is
-12 or -12 -1 x -1 is 1 but then you multiply it by -1 again it turns negative -1 would
work, -2 would work, -3 would work, -1/2 would work. The point is that simply a statement
telling us a rule of exponents that you will learn later but I am bringing it up here now,
2:00
which is to say that if you square negative number it is positive, but if you cube a negative
number it is negative and the only way X2 can be less than 0 is if X itself is negative.
Now what is X, remember we talked about that before, we don’t actually care what X is and
in this case we are not able to definitively know what X is, but we know something about
the nature of X and specifically we know that X is negative in all cases it will be negative,
which brings us to the question is X greater than 0. According to statement one, no, but
you know what the very fact that we were able to answer no means that statement number 1
is sufficient and it may sound like I am beating a dead horse and I apologize if you are feeling
like you know what, geez come on get to the point, you have gone over this and over this
3:01
and over this.
I can’t tell you how many times and you may be sitting there still trying to get your
mind around this where when you realize that answer is no students just want this for some
reason just think means that statement is not sufficient, no, no. The word “no” means
“no, no,” so they think it is not sufficient, that is not the case. The very fact again
that you can answer the question even if the answer happens to be no means you have been
given enough information statement one is sufficient so we cross off answer choices
BC and E.
I will make it even more concrete for you. Remember what we have said you do the brain
work, what would have enabled us to answer this question? Well obviously if we knew something
about the nature of X definitively, but what if we knew exactly what X was, what if statement
2 tells us that 3X equals -3. Is that sufficient or not? Well we get a few to the brainwork
beforehand and you said, okay, what information, obviously if they give me X. I mean if they
4:00
just tell me what X is that would be sufficient to answer the question that is essentially
what they have done here, haven’t they.
I mean I said we don’t actually need to solve for X but the bottom line is we all know just
looking at that that we could solve for X definitively and if you go too far and actually
do it I encourage you not too. I encourage you just to realize, hey one equation, one
variable I could solve for X and once I know X I could answer the question. I don’t care
whether the answer is yes, I don’t care whether the answer is no, the point is I can answer
the question so I don’t get confused, but never the less let’s say you do and you realize
X is -1 and you look up here is X greater than 0? No, X is -1.
Again, answer the question no, but the very fact that you were able to answer no means
you were given enough information both statements individually so either statement is sufficient
to answer the question even though the answer of the question happens to be no. To the extent
that you can avoid actually answering the question we will help you avoid a lot of confusion.
5:04
You see a statement like that, actually sometimes finding out the answer can be more confusing
than anything just realize you have been given enough information to find X therefore you
can answer the question, but never the less I just want to very clear.
I wanted to be very specific and understand that if you can definitively answer the question
one way or the other the statement is sufficient.
5:23
Dominate the GMAT
GMAT Data Sufficiency: Part II
Instructor Brett Ethridg
For more GMAT Exam and tips visit: DOMINATEtheGMAT.com