Archives For Stacey Koprince

gmat 750+A few months ago, I wrote a couple of articles targeted toward those students looking for a super-high score (one for quant, one for verbal). I challenged students to answer those questions in much less time than we typically average on test questions.

Well, I’m back with another one in the series. This problem is a bit different though: it’s from our Challenge Problem archive, a question bank consisting of what we call 800+ level problems. (Some might qualify as 750+ but most are harder than anything you’ll ever see on the real test.)

Do you need to be able to answer a question like this in order to score 750+? Absolutely not. (In fact, after my colleague Ron Purewal submitted this question, I tested it out on several of my fellow instructors, all of whom have scored 760+ on the test. Not everyone answered correctly.) Mostly, I’m offering this to stretch your brains, drive you a little crazy, and make one important point (see my second takeaway at the end).

If, however, quant is your strength and you’re hoping to score 51 in that section—you can certainly score 51 without getting this one right, but if you do get this one right in 2 minutes, then you know you’re ready for the quant section.

One more tidbit before we dive in. I chose this question because it is SO very hard. As of right now (as I’m typing this), 254 people have tried this problem and 44 have answered it correctly.

Do a little math here. What percentage of people answered the question correctly?

17%. Random guess position is 20%. Wow.

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I’ve talked to a ton of students recently who were surprised by some detail of test day—and that detail affected their performance. In most of these cases, the “surprising” detail was actually exactly what should have happened, according to the official rules.gmat test day So let’s talk about what’s going to happen when you finally get in there to take the test.

When you arrive

There will be some kind of outer waiting area, followed by an inner office containing the biometric equipment and finally the “inner sanctum”: the testing room.

When you first arrive, you’ll be asked to read (and digitally sign) a bunch of legalese. Basically, you’ll promise not to share anything that you see with anyone else and you affirm that you’re only taking the test for the purposes of applying to business school. You have to sign this document or you won’t be allowed to take the test.

You’ll also be asked for your ID. Check the guidelines to determine what kind of ID you must bring. Further, when you’re registering for the test, make sure that the name and birthdate you enter into the registration system match exactly what’s written on the piece of ID you’ll use to enter the test center.

But wait! You’re not done with security yet. They’ll take a digital photo of you. You’ll also have the veins in your palm digitally scanned—turns out our palm veins are even more unique than fingerprints. Who knew?

Finally, before you enter the inner sanctum, you’ll be asked to place all of your belongings (except for your ID) into a locker to which you will have the key. Everything goes in this locker: your wallet or purse, your money, your mobile phone, your keys, everything. Do not bring any study notes into the test center with you; your test will be cancelled immediately even if you simply leave these in your locker! Don’t use any electronic devices at any time—not your phone, not your iPod, nothing. Do not write anything down during the breaks, even if you’re just writing down your grocery list. Don’t give them any reason to think that you might be cheating.

Starting the test

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gmat meteor passage 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!).

Ready for the question? Give yourself about 1.5 minutes to answer.

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.

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Are you feeling incredibly stressed out when you sit down to study for the GMAT? (Or maybe I should ask, who isn’t?) Do you find it hard to concentrate on the task at hand?

Researchers at the University of California at Santa Barbara recently published the results of a study following 48 undergrads seeking to boost “cognitive performance.” Jan Hoffman details the research in a blog post over at The New York Times; here’s a summary.

The Motivation

“We had already found that mind-wandering underlies performance on a variety of tests, including working memory capacity and intelligence,” said Michael D. Mrazek, (quoted from the NYT blog post)

Ah, yes, “mind-wandering.” We’ve all had this experience. We’re taking a test, the clock is ticking, and we keep finding ourselves thinking about something other than the question we’re supposed to be answering right now. Maybe we’re stressing about our score. Maybe we’re thinking about applications. Maybe we’re even distracted by work, significant others, family, or other issues that have nothing to do with the test!gmat meditation

How do we stop fixating on other things and concentrate on the task at hand? This study tried to find out.

The Study

First, the students were given one verbal reasoning section from the GRE (fairly similar to the GMAT, except that the GRE emphasizes vocabulary more heavily than grammar). They also completed a task that measured their working memory. These tests are the “baseline” results.

The students were split into two groups; let’s call them Group M and Group N.

Group M attended meditation classes four times a week; these students learned lessons on “mindfulness,” which focuses on breathing techniques and helps to minimize distracting thoughts.

Group N attended nutrition classes, designed to teach these students healthy eating habits.

Afterwards, the students were given another GRE verbal section and another task to measure working memory. The performance of students in group N stayed the same; the nutritional studies didn’t make a difference.

Group M students, however, improved their GRE scores by an average of 12 percentile points! Here’s the best part: the study took just two weeks. You read that correctly: these students improved their verbal scores by 12 percentile points in just two weeks.

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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!).

Ready for the question? Give yourself about 1.5 to 2 minutes to answer.

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

gmat meteor streamThis 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.
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gmat reading comprehensionIn 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.”

Here’s how to read

When you’re reading an RC passage, think about:

(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.

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gmat exerciseI just read a really fascinating post on the New York Times’ Well blog. We’ve known for a long time that exercise has a whole host of good benefits, including benefits associated with memory. Two recent studies have delved even deeper into how this works.

How does exercise help memory?

In the blog post, New York Times journalist Gretchen Reynolds details the two new studies – one conducted on humans and the other conducted on rats.

In the human study, elderly women who already had some mild cognitive impairment were split into three groups. One group lifted weights, the second group engaged in moderate aerobic exercise, and the third group did yoga-like activities.

The participants were tested at the beginning and end of the 6-month exercise period and the results were striking. First, bear in mind that, in general, we would expect elderly people who are already experiencing mental decline to continue down that path over time. Indeed, after 6 months, the yoga group (our “control” group) showed a mild decline in several aspects of verbal memory.

The weight-training and aerobic groups, by contrast, actually improved their performance on several tests (remember, this was 6 months later!). In particular, these groups were not losing as much of their older memories and they even became faster at some spatial memory tests involving memorizing the location of three items. In other words, the women were both better at making new memories and better at remembering / retrieving old ones!

Another group of researchers conducted a similar study, only this time rats were getting some cardio in or lifting weights. (The rats ran on wheels for the cardio exercise and, get this, for the weight lifting, the researchers tied little weights to the rats tails and had them climb tiny ladders!)

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gmat pumpRaise 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.

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