The GMAT exam is as much about speed as it is about accuracy. If you know all the tips to tackle the GMAT syllabus, but you don’t know how to crack GMAT questions in time, the scoring algorithm will penalise you. In this MBA Crystal Ball post, the experts from GoGMAT provide ideas on how to solve difficult GMAT questions that may seem simple at first.
GMAT tips: How to crack GMAT exam questions in time
With roughly two short minutes in which to read, solve, and answer each problem in the GMAT quantitative section, you can hardly be blamed for expecting simple and elegant solutions. The truth, however, is that this is not always the case. Although solutions (short-cuts) that allow you to bypass strenuous and extensive calculations often do exist, to count on it as you approach this vital section may lead you to search too long, or worse, follow a wild-goose chase.
If you really want to crack GMAT exam questions and get a high score, your aim should be to analyze each question individually without any preconceived notion or predetermined template for resolution. Don’t think too long—start solving immediately with the first solution method that comes to mind, and constantly reevaluate your progress and your options.
Remember that the GMAT quantitative section assesses a wide array of problem-solving skills, not just your aptitude with mathematics. Knowing how not to solve a problem can be just as important as knowing how to solve it. Correctly answering a question in this section is not a one-step process.
First, you must read and understand the problem quickly.
Then, you must associate each question with a certain category (even though its answer can draw on a number of different areas of mathematics or logic); this step is not always as easy as it seems and it already plays a part in informing your resolution process. You should ask yourself, for example, does this question focus on geometry, algebra, or number properties? While accurately identifying what is being tested doesn’t guarantee correct answers, inaccurate identification it can lead you on a winding path to nowhere that will, if you pursue it unwaveringly, leave you frustrated and short of time for the remainder of the section.
The last step is the solution itself, i.e., doing the algebra, calculations, diagrams, or whatever is necessary to arrive at the correct answer. You may well be the best and fastest person on the planet in this last step, but if you neglect the previous steps your score will suffer either from incorrect answers (from, for example, misreading questions) or insufficient time to answer all the questions.
Keep in mind that even though the GMAT does not contain university level mathematics (e.g., calculus), anything at a lower level is free game. There is no “typical” GMAT problem-solving process.. The format and content of questions can vary greatly, as can the ideal or possible solution methods.
Every question is unique. A question may draw on probability, number theory, geometry, algebra, or any combination of these and other math topics. It may be solved through a combination of pure logic and trivial arithmetic, or it may require you to perform several time-consuming calculations, approximations, or trials intended to test not your thinking but rather your speed, effectiveness, and ability to remain focused and error-free throughout a complex process. Both the elegant and the not-so-elegant solution methods integral to the quantitative section.
It is crucial therefore to accept that there is no Holy Grail solution methodology; seemingly far-fetched solutions may apply. The following GMAT practice question presents a real example:
A non-square rectangle is inscribed within a circle of radius r. Which of the following could be the rectangle’s perimeter? You are then presented with five plausible expressions for the rectangle’s perimeter.
In this case, you have no choice but to test and exclude each choice in turn until you find the correct answer. Consider what’s required to answer this question:
- You will have to be familiar with geometric properties and the Pythagorean theorem;
- Either know the quadratic formula or be comfortable with factorization;
- Know the table of trigonometric values by heart for the common non-trivial angles pi/6(60º), pi/4(45º) and pi/3(60º);
- Be comfortable simplifying and manipulating algebraic expressions.
It seems very far-fetched and it’s certainly not pretty, but that is precisely what makes this question so hard. You can waste a lot of time trying to find a nice, quick abstract solution. Alternatively, you can begin to solve it immediately by the process of elimination. If you conclude prematurely that this method is far too time-consuming to be the right one, you can waste a lot of time unsuccessfully trying to find the nice, quick abstract solution, only to give up entirely—and you were on the right track to begin with!
As you solve, keep an open mind. Take a little time to think of other, faster approaches, but don’t go into a question thinking that an elegant solution necessarily exists.
It’s perfectly fine—in fact it’s advisable—to start working on a question, using the first solving method that comes to mind. Even when your mind goes blank, sometimes simply drawing diagrams or rewriting and simplifying expressions enables you to see the question in a different light, leading to a solution.
You may reach what seems like a dead end only to notice that you’re stalled at a stage where it is now the work of a moment to check each answer choice, though it would have been prohibitive at the outset. The exam is multiple choice, so it doesn’t matter at all how you find the answer, so long as you find it in time.
Look at this simple example that illustrates the point:
What is the probability that the sum of one roll of three eight-sided dice (1-8) is odd?
You could begin to attack this problem the same way you approach most probability problems, by listing all the possible outcomes. You might write down the eight possible outcomes of the first die and then, in tree diagram style, add the possible outcomes for the second die to each of the first eight.
This, however, is where you should notice, shortly after you started writing down the sums of the first and second roll outcomes, that these sums alternate in an even-odd fashion and that they will do so regardless of the number of dice rolled or their number of faces (so long as it is even).
At this point, you need not complete your diagram (this would take you a very long time indeed); you already know that the answer must be ½, or B. As you see, you didn’t have to spot the elegant solution immediately in order to answer the question quickly; you simply stumbled upon it as you worked. It might have taken you longer to realize the simple logic behind the question if you had tried to find it without starting to explore the obvious method immediately on paper.
Study wide and deep—the material applicable to solution may be broader than you think (e.g. formulas, properties, trigonometry table, and so forth). We hope this article gives you tips on how to crack GMAT exam questions in time. If you’re well prepared, solve pragmatically, and you will succeed.
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