This tip for improving your GMAT score was provided by David Newland at Veritas Prep.
Problem Solving and Data Sufficiency require many of the same mathematical tools and techniques. Problem Solving, however, is different from Data Sufficiency in one big respect. Data Sufficiency has answer choice E: “Statement (1) and (2) together are not sufficient to answer the question asked, and additional data are needed.”
This means there is always the chance that a Data Sufficiency question simply lacks the information needed to answer the question. Saying “this can’t be answered with the information given” is a legitimate answer to a Data Sufficiency question—after all, choice E is correct about 20 percent of the time.
For this reason you should never make any assumptions on data sufficiency. Always check such things as nonintegers, positive vs. negative, and the numbers zero and 1. If you do make an assumption on Data Sufficiency, there’s an excellent chance you will fall into a trap and choose the incorrect answer.
Problem Solving Is Different
On problem solving, “The answer cannot be determined from the information given” or even “none of the above” is rarely an option. Instead, you are typically given five answers involving numbers and/or variables. This means your only choices are either to come up with an answer to the question, using the information that you are given, or simply to guess at the problem. Saying it cannot be solved is not a legitimate choice on Problem Solving.
In other words, Problem Solving questions can be answered—maybe not by you at that very moment—but the information is there to solve the problem. It is for this reason that you may need to give yourself the “benefit of the doubt” on Problem Solving.
When in Doubt, Make the Necessary Choice
On a problem-solving question, if you have a choice of assuming, for example, that you have similar triangles on a problem, and if having similar triangles seems to be the only way to solve that problem, you better proceed as if you know that those triangles are similar.
There is no harm in making an assumption on Problem Solving if the choice is between making that assumption and being unable to solve the problem at all. When in doubt, read the problem in the way that is going to allow you to get an answer.
For example, what if you knew that a particular answer had to be 5333, and none of the answer choices gave you that exact answer, yet, one answer choice was 153? You cannot remember if you can combine bases with the same exponent, but it is the only answer choice that is not clearly wrong. So make the necessary choice. Combine those exponents.
What if you have a triangle perfectly inscribed in a circle? The longest side of the triangle is the diameter of the circle. If you could only remember whether that diameter was the hypotenuse of the triangle. Is that angle 90 degrees? If there is no other way to solve the problem, make that angle 90 degrees and go. Geometry has many special properties, and you are likely to forget one occasionally. It is better to take the only possible route if it looks as if you can get a solution quickly. Your only other option is to guess. And if you trust your instincts, you’re more likely not only to be correct (you probably do remember that principle correctly even if you’re not certain) but also to save time and maintain a positive level of confidence, which will help you on future questions.
Many people say that Data Sufficiency has an advantage over Problem Solving in that you do not always have to do all the math. But Problem Solving has an advantage of its own. In Data Sufficiency, if you forget whether a certain property applies to the problem in front of you, you are in trouble. The answer could always be choice E, “not enough information.” With Problem Solving, you can give yourself the benefit of the doubt.
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