Determining How Much Time to Spend on GMAT Quant Questions

On the GMAT, you will be asked to answer multiple questions in a relatively short period of time. One of the main difficulties test takers have with the GMAT is that they run out of time before finishing all the questions. For the quant section in 2019, there are 31 questions to solve in 62 minutes, which gives an average time per GMAT quant question of exactly two minutes. Since you don’t want to finish at the 61:59 mark (unless you’re MacGyver), you can figure two minutes per question as a good target, but ideally you’re solving a few GMAT questions in less time than the “official” average time per question. The good news is that most GMAT questions can easily be solved in less than the two minutes per question you are allotted.

Unfortunately, many test takers struggle with the basic question of “how much time should I spend per question on the GMAT?” as there are dozens of different theories online and various suggestions from friends and coworkers who’ve taken the exam before and who have “cracked the code.” Many people swear that the first few questions are the only ones that matter. Others tell you the middle of the exam is irrelevant and you should speed through it. One popular piece of advice is to skip any question that will take you more than 4 minutes, as many test takers end up spending four or five minutes on questions that they ultimately get wrong. This is usually because they do not understand what they are trying to solve, so they’re trying to interpret the question, translate it into more familiar language, and solve it all at once. Needless to say, this is a recipe for wasting a lot of time on a single GMAT question.

One important thing to remember is that you won’t have a calculator on the exam, so blindly executing mathematical equations will be an exercise in futility. Most GMAT questions could easily be solved if only we had 5 minutes per question. While this is true, it’s akin to saying we’d be Canadian if only we’d have been born in Canada (and likely more polite and colder, eh). It’s true, but it doesn’t help the current situation because it ignores the situation at hand. Yes, almost anyone can write all the numbers from 1 to 100 in 5 minutes, or list the 32 possibilities of flipping 5 coins on a piece of paper, but time is of the essence and any precious seconds you save on question 5 can potentially help you on question 25. So your overarching goal should always be to spend as little time as necessary to get a question right on the GMAT.

If the numbers seem large, the first thing to do is to determine whether the large numbers are required or just there to intimidate you. The difference between 15^3 and 15^13 is staggering, and yet most GMAT questions could use these two numbers interchangeably, because the actual number is irrelevant. What the GMAT is likely testing here is probably unit digits or common factors, so breaking the number into some amount of threes and fives is all you need to do to solve the question quickly. Recognition of common GMAT themes is a big way to reduce your average time per GMAT question!

Once you determine whether the bloated numbers truly matter, you need to ascertain how much actual work is required. If the question is asking you for something fairly specific, then you might need to actually compute the math, but if it’s a general or approximate number, you can often eyeball it. It doesn’t take very long to determine that 3/11 is a bigger number than 3/13, so don’t be fooled into trying to put the fractions on a common denominator of 143! The same numerator on a larger denominator will yield a smaller number. It’s like ordering a pizza for your family and your ingrate cousins invite themselves over, all of a sudden there’s less Hawaiian pizza for you (is that a bad thing?). Understanding these mathematical properties helps you save time and brings down your average time per question because you’re shortcutting a lot of rote calculations.

Even if you end up having to execute calculations, you can usually estimate the correct answer and then scan the answer choices. We recall a fun question from a past Official Guide that was concerned with the number of seconds in an hour. While multiplying by 3,600 is not impossible without a calculator, it is time-consuming for the average GMAT student, so perusing the answer choices can help narrow down the options. Furthermore, we would argue that estimating and eliminating impossible answer choices is very much the goal of the GMAT. You, the test taker, will never be faster than a computer, so any brute force approach you undertake will necessarily be inefficient. What you possess that computers don’t (yet??) is critical reasoning, the ability to ascertain and estimate based on incomplete data. This is what the GMAT is trying to measure and improve among test takers – efficiency and critical thinking matter in business, so the GMAT is often testing how you can think critically to solve a question in considerably less time than the brute force method would suggest you need to take.

Even in Data Sufficiency, determining how precise the calculations need to be can save you a lot of time and aggravation, and will shorten the average time you take on a question. There are no various numbers to browse through, but the idea of estimating and shortcutting still applies in many questions. Data Sufficiency problems also typically take less time to complete than Problem Solving questions, so you can reduce your time per question on these unique GMAT questions by having a solid approach to cutting through the Data Sufficiency abstraction.

Let’s take a look at a question that can be somewhat daunting because of the numbers involved, but is rather simple if we correctly determine what needs to be done:

If 1,500 is the multiple of 100 that is closest to X and 2,500 is the multiple of 100 closest to Y, then which multiple of 100 is closest to X + Y?

(1) X < 1,500

(2) Y < 2,500

(A) Statement 1 alone is sufficient but statement 2 alone is not sufficient to answer the question asked.

(B) Statement 2 alone is sufficient but statement 1 alone is not sufficient to answer the question asked.

(C) Both statements 1 and 2 together are sufficient to answer the question but neither statement is sufficient alone.

(D) Each statement alone is sufficient to answer the question.

(E) Statements 1 and 2 are not sufficient to answer the question asked and additional data is needed to answer the statements.

The first step here is to try and understand what the question is asking. It can be a little confusing so you might have to read it more than once to correctly paraphrase it. Essentially some number X exists and some number Y exists, and the question is asking us what X + Y would be. The only information we get about X is that 1,500 is the closest multiple of 100 to it, meaning that X essentially lies somewhere between 1,450 and 1,550. Any other number would lead to a different value being the closest multiple of 100 to it. Number Y is similar, but offset by 1,000. It must lie between 2,450 and 2,550. This is already much simpler to understand, and a parallel GMAT question with this information already provided would be much quicker to solve.
At this point it’s worth noting that the problem would be exactly the same with 100 and 200 instead of 1,500 and 2,500. So why are four-digit numbers chosen here? Simply for the GMAT to daunt the reader and trap you into spending more time on the question than is necessary. It’s also very likely that a more difficult version of this same question would be 15,000 and 25,000, or perhaps 1.5 and 2.5 million. The logic, approach and general solution will be the same in all instances, but the average time taken to solve will increase as the numbers grow larger and larger (much like the bushes outside Veritas headquarters).

Without even looking at the two statements, let’s see what we can determine from this problem: Essentially if we add X and Y together, the smallest amount we could get is (1,450 + 2,450 =) 3,900. The largest number we could get is (1,550 + 2,550 =) 4,100. The sum can be anywhere from 3,900 to 4,100, and therefore the closest multiple of 100 could be 3,900, 4,000 or 4,100, depending on the exact values of X and Y. This tells us that we have insufficient information through zero statements, which isn’t particularly surprising, but it also sets the boundaries on what we need to know. There aren’t dozens of options; we’ve already narrowed the field down to three possibilities. Now to acquire 3 roses like a GMAT bachelor.

(1) X < 1,500 Looking at statement 1, we can narrow down the scope of value X. Instead of 1,450 < X < 1,550, we can now limit it to 1,450 < X < 1,500. This reduces the maximum value of X + Y from 4,100 to under 4,050. This statement alone has eliminated 4,100 as an option for the closest multiple of 100, but it still leaves two possibilities: 3,900 and 4,000. Statement 1 is thus insufficient. This does not take much time to determine, and already eliminates two answer choices (A and D, the two that indicate that statement 1 would be sufficient on its own) very quickly.
(2) Y < 2,500 Looking at statement 2 on its own, we now have an upper bound for Y, but not for X. This will end up exactly as the first statement did, as we can now limit the value of Y as 2,450 < Y < 2,500. This is fairly clearly the same situation as statement 1, and we shouldn’t spend much time on it because we’ll clearly have to combine these statements next to see if that’s sufficient.
(1) X < 1,500

(2) Y < 2,500 Combining the two statements, we can see that the value of X is: 1,450 < X < 1,500 and the value of Y is 2,450 < Y < 2,500. If we tried to solve for X + Y, the value could be anywhere between 3,900 and 4,000, so 3,900 < X+Y < 4,000. This still leaves us in limbo between two possible values. To illustrate, let’s pick X to be 1,460 and Y to be 2,460. Both satisfy all the given conditions and give a sum of 3,920, which is closest to 3,900. If we then picked X to be 1,490 and Y to be 2,490, we’d get a sum of 3,980. The second situation clearly gives 4,000 as the closest multiple. If we can solve the equation using valid arguments and yield two separate answers, we have to pick answer choice E. These types of daunting GMAT questions can appear to require quite a bit of time per question because of the big numbers and the ambiguous wording, but the underlying material on these questions will never be something that can’t be solved in a matter of minutes. The difficulty often lies in determining how much work we really need to do to solve the question at hand. Students often lament that they need more time per question on the GMAT, when in fact they often just need a better approach to abstract or complicated questions. The old adage is that you get A for effort, but that’s applicable when you tried earnestly and failed. On the GMAT, you want to put in as much effort as is needed, but the only A you’re really striving for is the vaunted “Admitted.” Ron Awad is a GMAT instructor for Veritas Prep based in Montreal, bringing you weekly advice for success on your exam.  After graduating from McGill and receiving his MBA from Concordia, Ron started teaching GMAT prep and his Veritas Prep students have given him rave reviews ever since.

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