### Archives For What’s On the GMAT

Learn about the topics covered on the GMAT, both in the verbal and the quant section as well as in the AWA.

One of the hardest parts about becoming an instructor with Manhattan GMAT was relearning how to solve GMAT questions. That sounds absurd, considering I had already scored a 780 on the GMAT when I applied to become an instructor, but it’s true. During the interview process, I went through online and in-person classroom simulations with 99th percentile instructors playing students, testing my ability to explain a question using algebra instead of plugging numbers or using a rate chart instead of adding rates. Over the years, I’ve found that many of our instructors felt the same way: overwhelmed by how hard it is to go along with someone else’s preferred method without skipping a beat. Ultimately, I realized that teaching the GMAT is a hundred times harder than taking the GMAT because every question has several valid ways of being solved.

Which leads to the problem of what solution is the BEST solution. Any student who has worked with me over the years has heard me say the following- “I don’t care what method you use to solve a problem. But I do care that you get great at that method.” It’s the reason why the Official Guide has an explanation for each quant problem and Manhattan has an OG Companion with different explanations, along with online video explanations that will sometimes differ from either of those methods. With so many different ways of solving a question, it’s important to not get bogged down finding the best way to solve a problem, but instead focus on finding the fastest way from start to submit.

So with that said, over the next few months, I’d like to share a few methods that I personally use when solving a few different types of GMAT questions. Some of these methods might click for you, and I hope you practice them. Some of them won’t and I hope you stick with a method that works better for you. So without further ado- let’s take a look at a fairly straightforward GMATPrep® problem and think about how you would attack this question:

A sum of \$200,000 from a certain estate was divided among a spouse and three children. How much of the estate did the youngest child receive?

(1)  The spouse received 1/2 of the sum from the estate, and the oldest child received 1/4 of the remainder.

(2)  Each of the two younger children received \$12,500 more than the oldest child and \$62,500 less than the spouse.

The first two things that I notice about this problem is that it is a word problem, giving us a real-world scenario, and a value Data Sufficiency question, asking us to find a single value for the amount that the youngest child received. And if I wanted to set this up algebraically, I could assign variables (s = spouse, x, y, z = oldest, middle, youngest child), write out several equations (s + x + y + z = 200,000. (1) s = 1/2*200,000; x = 1/4 * (1/2*200,000); y + z = 75,000. (2) y = z; z = x + 12,500; z = s − 62,500), and eventually solve for z using Statement 2: the correct answer is (B). Different students at different levels of comfort with Data Sufficiency will be able to stop at different points after realizing that there either will or will not be a single variable in the equation that they’ve set up.

Imagine two friends, Gina and Tina, who are going to a speed-dating event. Gina really, really wants a boyfriend. Tina is just going because Gina dragged her there, and she’s only willing to date someone who is perfect for her.

At the event, Gina finds herself liking every guy that she meets: “Guy #1 is smart and successful, so it makes sense that he’s proud of his accomplishments. Guy #2 is really funny and clever. The waiter just didn’t understand his jokes.” Tina, on the other hand, has a very different impression of these guys: “Guy 1 has been bragging about himself the whole time, and seems arrogant. Guy 2 thinks he’s funny, but he’s actually being cruel and making fun of people.”

At the end of the event, Gina can’t decide which of the guys she likes best, because she’s found reasons to like all of them… and she’s overlooked any reasons not to like them. Tina, however, was looking for reasons not to date these guys, so she noticed the dealbreaker flaws. She manages to whittle the list down to one guy whose personality matched hers.

Of course, dating is subjective, and what might be a dealbreaker for one person might be fine for someone else. On the GMAT, though, there are definitive right and wrong answers, and we have to learn how to spot the wrong ones.

## Look for Dealbreakers

When it comes to Reading Comprehension on the GMAT, you want to act like Tina, not Gina! You will often be presented with questions whose answer choices all seem to have appealing qualities. If you’re looking for what makes an answer right, you may overlook certain critical flaws, and talk yourself into a wrong answer. If you’re looking for what makes an answer wrong, though, you’re a lot more likely to notice those deal-breaking flaws!

Originally, I was only planning to do one question from the Meteor Stream passage. But this one is so much fun, I figured why not?

Yes, I’m being sarcastic. I don’t think anybody finds this passage “fun.” : )

In fact, that’s why I want to look at another problem with you—this thing is kind of a nightmare!

Okay, if you haven’t already, read the Meteor Stream passage. Note that this comes from the free set of questions in GMATPrep® (not from the practice CATs). Here’s the link to the first question we did (though you don’t need to try that one before continuing with this article).

Click the first link in the previous paragraph and open up that passage in a separate window (I’m not going to show it here because it’s so long!).

## The Question

“The author states that the research described in the first paragraph was undertaken in order to

“(A) determine the age of an actual meteor stream

“(B) identify the various structural features of meteor streams

“(C) explore the nature of a particularly interesting meteor stream

“(D) test the hypothesis that meteor streams become broader as they age

“(E) show that a computer model could help in explaining actual astronomical data”

## Solution

This is a detail question, so we’re going to use our notes and any clues in the question stem to know where to look. The question stem gives us one huge clue: it refers specifically to the first paragraph.

Next, the question says “in order to.” This language typically points to a Why question—that is, why did the author talk about or include something? In this case, the question asks why someone conducted the research described in the first paragraph.

Take a look at your notes. Mine are below, but everyone will have somewhat different notes.

Last time, we took a look at the Meteor Stream passage from the free set of questions that comes with GMATPrep® (not from the practice CATs). Click the link in the previous sentence and open up that passage in a separate window (I’m not going to show it here because it’s so long!).

## The Question

“The passage suggests that which of the following is a prediction concerning meteor streams that can be derived from both the conventional theories mentioned in the highlighted text and the new computer derived theory?”

[Note: when this question is given during the test, the phrase Conventional theories is also suddenly highlighted in yellow in the passage. This text appears at the start of the second-to-last sentence of the first paragraph.]

“(A) Dust particles in a meteor stream will usually be distributed evenly throughout any cross section of the stream.

“(B) The orbits of most meteor streams should cross the orbit of the Earth at some point and give rise to a meteor shower.

“(C) Over time the distribution of dust in a meteor stream will usually become denser at the outside edges of the stream than at the center.

“(D) Meteor showers caused by older meteor streams should be, on average, longer in duration than those caused by very young meteor streams.

“(E) The individual dust particles in older meteor streams should be, on average, smaller than those that compose younger meteor streams.”

## Solution

This is a detail question, so we’re going to use our notes and any clues in the question stem to know where to look. The question stem gives us one huge clue: it actually highlights a portion of a sentence in the first paragraph.

Next, the question says “the passage suggests,” so this is an inference question. Finally, the question is asking for a prediction that can be drawn from both the conventional theories and the new computer theory—in other words, where do these two theories agree?

Take a look at your notes. Mine are below, but everyone will have somewhat different notes.

In the past, we’ve done some “one-off” review of parts of RC passages, but this time I’ve got a full one for you. In this article, we’ll look at how to get through this thing (and what to avoid). Next week, we’ll do a question or two.

I chose this passage from the free set of questions that comes with GMATPrep® (that is, it doesn’t actually show up in the practice CAT itself). It’s a longer passage, so give yourself approximately three minutes total to get through.

## The Passage

“A meteor stream is composed of dust particles that have been ejected from a parent comet at a variety of velocities. These particles follow the same orbit as the parent comet, but due to their differing velocities they slowly gain or fall behind the disintegrating comet until a shroud of dust surrounds the entire cometary orbit. Astronomers have hypothesized that a meteor stream should broaden with time as the dust particles’ individual orbits are perturbed by planetary gravitational fields. A recent computer-modeling experiment tested this hypothesis by tracking the influence of planetary gravitation over a projected 5,000-year period on the positions of a group of hypothetical dust particles. In the model, the particles were randomly distributed throughout a computer simulation of the orbit of an actual meteor stream, the Geminid. The researcher found, as expected, that the computer-model stream broadened with time. Conventional theories, however, predicted that the distribution of particles would be increasingly dense toward the center of a meteor stream. Surprisingly, the computer-model meteor stream gradually came to resemble a thick-walled, hollow pipe.

“Whenever the Earth passes through a meteor stream, a meteor shower occurs. Moving at a little over 1,500,000 miles per day around its orbit, the Earth would take, on average, just over a day to cross the hollow, computer-model Geminid stream if the stream were 5,000 years old. Two brief periods of peak meteor activity during the shower would be observed, one as the Earth entered the thick-walled “pipe” and one as it exited. There is no reason why the Earth should always pass through the stream’s exact center, so the time interval between the two bursts of activity would vary from one year to the next.

“Has the predicted twin-peaked activity been observed for the actual yearly Geminid meteor shower? The Geminid data between 1970 and 1979 show just such a bifurcation, a secondary burst of meteor activity being clearly visible at an average of 19 hours (1,200,000 miles) after the first burst. The time intervals between the bursts suggest the actual Geminid stream is about 3,000 years old.”

(1) What words or parts of the sentence are so complex that I’m going to ignore them for now?

(2) When can I stop reading and start skimming?

(3) When do I have to start paying close attention again?

Below, I go through each paragraph, noting various things. Normal text means: I did read this but didn’t pay extra attention to it. Boldface text really stood out for me: my brain perked up and paid attention.

“Many a true word is said in jest.”—I don’t know, but I heard it from my mother.

I think that Critical Reasoning is my favorite part of the exam because it is the purest of the pure.  I’ve written before that the GMAT is an aptitude test rather than a knowledge test.  On the simplest level, in both the quant and the verbal, the exam tests a logic system: be specific, don’t assume, and don’t rationalize.  Nowhere is this more true than in Critical Reasoning—there is no mathematical foundation work nor are there grammar rules.  As Gertrude Stein used to say, “There is no there, there.”  Of course, she was talking about Oakland. . .fill in your own joke.  When I’m being* mean to students, I say, “If you know what all the words mean, you should get them all right.”

But students don’t get them all right.  Even those who know what all the words mean.  Why is that?  Because people think.  They assume, they rationalize, and they inject opinions.  Why is this bad?  Because it’s a game.  Critical Reasoning doesn’t take place in reality.  Here’s an analogy I thought up all by myself, so it isn’t in the Strategy Guide: Critical Reasoning bears the same relationship to reality that Monopoly does.  When you play Monopoly, you don’t think about how reasonable free parking or building hotels is, you exploit the rules.  It’s the same thing.  A lot of OG arguments involve medical issues, but you hardly ever care whether people live or die because that’s usually not the conclusion.   Play the game.

As a by the way, if students struggle with the CR, it’s often half of their trouble in the quant.  Folks are not specific; they read the question or the given incorrectly.  And they don’t recognize the types and patterns.  In other words, they don’t play that game.  However, folks fail to notice these mistakes because they are too consumed with worry about their math foundations.  Conversely, engineers with strong foundations also suffer here, especially in the DS because they try to use brute mathematical force instead of playing the game.  It is a behavioral problem.  People don’t do; they think.  Don’t think—much like in life, it only gets you into trouble.

Need to convert your Official Guide 12 problems to OG13 problems? Or visa versa? Check out our hand-dandy conversion guide for Quant problems, below. You can find our conversion guide for Verbal problems here.

Raise your hand if you love rate and work questions. They’re awesome, right? They tend to be fairly long, and the set-up is pretty complex, plus we get to build a table before we dive into the equations!

Oh, wait… no… those are all reasons why we can’t stand these problems.

Give yourself approximately 2 minutes to try the below GMATPrep® problem. When you’re done, take a look at it again and ask yourself, “Is there a better way to do this thing?”

* “Pumps A, B, and C operate at their respective constant rates. Pumps A and B, operating simultaneously, can fill a certain tank in 6/5 hours; pumps A and C, operating simultaneously, can fill the tank in 3/2 hours; and pumps B and C, operating simultaneously, can fill the tank in 2 hours. How many hours does it take pumps A, B, and C, operating simultaneously, to fill the tank?

“(A) 1/3

“(B) 1/2

“(C) 2/3

“(D) 5/6

“(E) 1”

Have you got an answer? Pick one anyway. Pretend it’s the real test: you can’t keep going till you pick an answer.