03 Feb 2017

GMAT Basics: Data Sufficiency


A while ago I wrote a blog piece about GMAT math in general. I mentioned a funny little question type unique to the GMAT called Data Sufficiency. Today, we are going to explore this novel question type in a little more detail. Hopefully you’ll get some sense of what it’s about and maybe how to go about dealing with it.

Ok, first things first. Out of the 37 total Quantitative questions on the GMAT around 15 are Data Sufficiency. I say around 15 because it’s an adaptive test and nobody really knows how they decide what they give you. Well, except for GMAC of course. About a fourth of the total questions are experimental and will not count toward your score. And before you ask, there is no way to know for sure which are experimental, so don’t try to figure it out while taking a test. Better yet, don’t even bother thinking about it. Personally, I like to think that if I make a mistake on a question it very well could be experimental and not count. Stay positive.

So, down to business. Below are the same directions you’ll see anywhere. This comes straight from the GMAT.


This data sufficiency problem consists of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements, plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of the word counterclockwise), you must indicate whether:

  • Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked.
  • Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked.
  • BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient to answer the question asked.
  • EACH statement ALONE is sufficient to answer the question asked.
  • Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.

A lot of words, but you should read it at least once. Please. Carefully. Here is my summary. You are going to get a question about math, usually pretty basic. Most frequently it’ll be something about arithmetic such as number properties or percents. (Seriously, they love themselves some number properties and percents.) Anyway. You will then get 2 statements. You then choose between the 5 set answer choices. These 5 answer choices are always the same. A) is statement 1 alone is sufficient, etc. You did read the directions above right?

This is where it gets a little funky. First I want to make sure we understand what sufficient means. It means you have enough information to answer the question. As in, you can find or derive the answer solely from the info given. Here is the important thing. Even though half the time the DS (Data Sufficiency) question asks you for an actual value, like “what is the value of x?”, the real question is “what combination of statements give you enough information to answer the question asked?” I’ve heard people say DS questions are “managerial questions.” I suppose as a manager you don’t need to find the answer, just ensure that the answer can be found. So really, your job is not to answer the math question given, but to answer the “managerial question,” which never changes. Initially it can be misleading. It takes a little getting used to. As I’ve said before, treat the test with respect and prep well. I’ll talk more about the how prep in future articles. Meanwhile, if you want more info or help, contact us. I’d love to help you train and gain.