Articles published in Quant

The Importance of Getting to No on the GMAT — Part 1

by

Social-No-Pt1Recently, a colleague of mine shared this very interesting puzzle published by the New York Times. (Thanks, Ceilidh!)

Go ahead and try it. I’ll wait. After you’ve tried the puzzle, you can read the short article that goes with it.

What did you learn about how humans tend to think? More important, what did you learn about how you think?

That tendency to look for the no, or to try to disprove something, is a trait shared by scientists, devil’s advocates, and great standardized test takers. You can learn to make this your natural reaction, too!

Read more

How to Tackle Every Single GMAT Problem (Seriously!) — Part 1

by

Wouldn’t it be nice to have one common thread among all GMAT problems you’ll ever do, something you do no matter what kind of problem or content area is being tested?

Blog-Tackle-Pt1

I’m here to answer your prayers. :)

Okay, obviously, there are many things you’re going to need to learn and practice in order to get a great GMAT score—these isn’t literally just one thing to learn. But it turns out that there is one set of principles tying together everything we need to do on the GMAT.

Read more

How to Get the Most out of the GMAT Official Guides

by

Blog-6-22-2015-OGs-3 (1)Now that the new 2016 Official Guide books are out, I’d like to talk about how to use these problems to get the most out of your study. I also want to talk about what not to do, as a lot of people end up essentially wasting these great study problems (not to mention valuable time!).

What should I NOT do?

Your goal is to learn from the Official Guide (OG) problems in such a way that, if you see something similar on the real test, you’ll recognize what to do on that new problem.

Keep some things in mind:

  1. Your goal is NOT to memorize how to do the problems that you’re studying. You won’t see these exact problems on the test! Can you tell me exactly how to do a particular problem? That’s great. But I care far more whether you can tell me how you know what to do and why you want to take the steps that you take. If you can, then you’ll know how to think your way through a new problem on the real test.
  2. Your goal is NOT to try to get everything (or even most problems) right. Sometimes, what you want to recognize fairly quickly is that you should guess immediately and move on. Other times, you want to recognize that your best strategy is to spend some time making an educated guess—and then move on. Still other times, you’ll have to be able to recognize that you initially thought you could do this one but it’s just not happening, so you’ll need to cut yourself off, guess, and move on.

Read more

Everything you need to know about the New Official Guides, Part 3

by

I have now done every last one of the new quant problems in both new books—and there are some really neat ones! I’ve also got some interesting observations for you. (If you haven’t yet read my earlier installments, start here.)

In this installment, I’ll discuss my overall conclusions for quant and I’ll also give you all of the problem numbers for the new problems in both the big OG and the smaller quant-only OG.

What’s new in Quant?

Now that I’ve seen everything, I’ve been able to spot some trends across all of the added and dropped questions. For example, across both The Official Guide for GMAT® Review (aka the big book) and The Official Guide for GMAT® Quant Review (aka quant-only or the quant supplement), Linear Equation problems dropped by a count of 13. This is the differential: new questions minus dropped questions.

That’s a pretty big number; the next closest categories, Inequalities and Rates & Work, dropped by 5 questions each. I’m not convinced that a drop of 5 is at all significant, but I decided that was a safe place to stop the “Hmm, that’s interesting!” count.

Now, a caveat: there are sometimes judgment calls to make in classifying problems. Certain problems cross multiple content areas, so we do our best to pick the topic area that is most essential in solving that problem. But that 13 still stands out. :)

The biggest jump came from Formulas, with 10 added questions across both sources. This category includes sequences and functions; just straight translation or linear equations would go into those respective categories, not formulas. Positive & Negative questions jumped by 7, weighted average jumped by 6, and coordinate plane jumped by 5.

Given that Linear Equations dropped and Formulas jumped, could it be the case that they are going after somewhat more complex algebra now? That’s certainly possible. I didn’t feel as though the new formula questions were super hard though. It felt more as though they were testing whether you could follow directions. If I give you a weird formula with specific definitions and instructions, can you interpret correctly and manipulate accordingly?

If you think about it, work is a lot more like this than “Oh, here are two linear equations; can you solve for x?” So it makes sense that they would want to emphasize questions of a more practical nature.

Read more

Everything you need to know about the New Official Guides, Part 2

by

OG2016-Ads-2The new Official Guide books are here! Last time, we talked about the Quant portion of The Official Guide for GMAT, aka the OG or the big book. In this installment, we’ll discuss the Verbal section of the big book. Later installments will talk about the Quant Review and Verbal Review (the smaller books), as well as question lists for the new questions.

(Note: I have not yet had time to analyze the IR problems that come via your special online access. I’ll get to that soon—the quant and the verbal are higher priority!)

Part 1 included an overview of the changes to the whole book; I’ve included that overview here as well (the next section!), in case you’re reading this installment first. (The only difference is one sentence in the first paragraph.)

What’s new in OG 2016?

Approximately 25% of the questions are brand new, and there are some beauties in the mix. As I worked through the problems, I marveled anew at the skill with which the test writers can produce what I call elegant problems. On the verbal side, I loved how some of the new questions wove meaning into the issue of Sentence Correction; if you have been focusing on grammar and shortchanging meaning, you’re definitely going to need to change your approach.

Read more

Everything you need to know about the New Official Guides, Part 1

by

OG2016-Ads-2The new Official Guide books are here! Aren’t you excited?!?

Okay, I realize that most people probably aren’t as excited as I am. But there are still some interesting and useful things to know about these new books as you get ready to take the GMAT. So let’s talk about it!

In this installment, I’ll discuss additions and changes to quant sections for The Official Guide for GMAT® Review 2016, aka the OG or the big book. Keep an eye out for later installments, in which I’ll discuss the verbal section of the big book, as well as the Quantitative Review and Verbal Review books. I’ll also be providing you with a list of the new questions, in case you decide to study from both the 2015 and 2016 editions.

If you haven’t already bought your official guide books, then do buy these latest editions—sure you might be able to get a discount on the 2015 editions, but since you have to spend money anyway, you might as well work from the latest and greatest.

If you have already bought the older editions and are debating whether to buy the new ones, too, then you’ve got a decision to make. On the one hand, there are a lot of great new questions in the 2016 editions. On the other, the 2015 edition already has a ton of problems; you may not need even more. If it were me, I’d wait until I’d used up the ones in the materials I already have. If I still felt that I needed more beyond that, then I’d consider getting one or more of the new books.

What’s new in OG 2016?

Approximately 25% of the questions are brand new, and there are some beauties in the mix. As I worked through the problems, I marveled anew at the skill with which the test writers can produce what I call elegant problems. On the quant side, I saw example after example in which the problem can be solved with little to no computation as long as you can decode and understand the fundamental concept underlying the problem—that’s the real test-taking skill!

Read more

New Edition of GMAT Advanced Quant: Study the Hardest Quant Questions

by

GMAT Advanced Quant Now AvailableI am super excited to announce a new edition of our GMAT Advanced Quant Strategy Guide! We worked hard on this book all of last year (yes, it takes a long time make a book!) and we hope that you find it to be a valuable addition to your GMAT preparation.

What is the Advanced Quant guide?

We created the Advanced Quant (AQ) guide a few years ago for people who want to get a top score (50 or 51) on the quant section of the GMAT.

Here’s the interesting thing: it doesn’t teach you a bunch of really hard math concepts. We teach all of those concepts in our five regular strategy guides (Algebra, Geometry, Word Problems, Number Properties, and Fractions, Decimals, & Percents). Instead, the AQ guide teaches you the next level of GMAT study: how to think your way through really hard quant problems.

What’s new in this edition?

A bunch of things! First, there are more than 50 brand-new, extremely hard problems. We actually removed some old ones that we thought were a bit too easy and replaced them with harder problems.

But that’s not all. Since the entire point of this book is how to solve better, we’ve updated some solutions to existing problems because we’ve discovered an even more efficient or effective way to solve.

We’ve also introduced a new organization method for working your way systematically through any quant problem. We’ve added or expanded lessons on test-taking strategies, such as testing cases on both problem solving and data sufficiency problems.

One student, who has already used the old version of AQ, asked whether we would provide a list indicating which questions are the new ones. I told him no. Not because I’m lazy or I don’t care, but because you don’t need such a list! If you’ve already tried the first edition and want to try this one, too, just start going through the book. If you hit a problem you remember, feel free to skip it. (Although maybe this is a chance to see if you really do remember what to do…and remember that we may offer an updated solution that you haven’t seen before.) If you hit a problem you don’t remember, then it doesn’t matter whether it’s old or new. It’s new to you right at this moment!

Who should use the AQ Strategy Guide?

First, you should have mastered most (if not all) of the material in our five main quant Strategy Guides. As I mentioned earlier, we do not actually teach you that math in this guide. We assume that you already know it.

As a general rule, we recommend that people avoid using this book until they’ve gotten to a score of at least 47 on a practice CAT. (Seriously. We say so right in the first chapter of the book!) I might let that slide a bit for certain students, but someone scoring below 45 likely does not have the underlying content knowledge needed to make the best use of the Advanced Quant lessons.

Note that, from an admissions standpoint, you may not necessarily need to score higher than 47. The scoring scale tops out at 51, so 47 is already quite high. Do a little research to see what you may need for the specific schools to which you plan to apply.

All right, that’s all I’ve got for you today. I’d love to hear what you think about the book. Which problem is your favorite? And which one do you think is the absolute hardest, most evil thing we could have given you? Let us know in the comments!

Check out our store to learn more about the new GMAT Advanced Quant Strategy Guide.

GMAT Problem Solving Strategy: Test Cases

by

3-19-TestCasesIf you’re going to do a great job on the GMAT, then you’ve got to know how to Test Cases. This strategy will help you on countless quant problems.

This technique is especially useful for Data Sufficiency problems, but you can also use it on some Problem Solving problems, like the GMATPrep® problem below. Give yourself about 2 minutes. Go!

* “For which of the following functions f is f(x) = f(1 – x) for all x?

(A) f(x) = 1 – x
(B) f(x) = 1 – x2
(C) f(x) = x2 – (1 – x)2
(D) f(x) = x2(1 – x)2
(E)  f(x) = x / (1 – x)”

 

Testing Cases is mostly what it sounds like: you will test various possible scenarios in order to narrow down the answer choices until you get to the one right answer. What’s the common characteristic that signals you can use this technique on problem solving?

The most common language will be something like “Which of the following must be true?” (or “could be true”).

The above problem doesn’t have that language, but it does have a variation: you need to find the answer choice for which the given equation is true “for all x,” which is the equivalent of asking for which answer choice the given equation is always, or must be, true.
Read more

When Your High School Algebra is Wrong: How the GMAT Breaks Systems of Equations Rules

by

2-17-HighSchool-2If you have two equations, you can solve for two variables.

This rule is a cornerstone of algebra. It’s how we solve for values when we’re given a relationship between two unknowns:

If I can buy 2 kumquats and 3 rutabagas for $16, and 3 kumquats and 1 rutabaga for $9, how much does 1 kumquat cost?

We set up two equations:

2k + 4r = 16

3k + r = 9

Then we can use either substitution or elimination to solve. (Try it out yourself; answer* below).

On the GMAT, you’ll be using the “2 equations à 2 variables” rule to solve for a lot of word problems like the one above, especially in Problem Solving. Be careful, though! On the GMAT this rule doesn’t always apply, especially in Data Sufficiency. Here are some sneaky exceptions to the rule…

2 Equations aren’t always 2 equations
Read more

Tackling Max/Min Statistics on the GMAT (part 3)

by

2-12-MinMaxP3

Welcome to our third and final installment dedicated to those pesky maximize / minimize quant problems. If you haven’t yet reviewed the earlier installments, start with part 1 and work your way back up to this post.

I’d originally intended to do just a two-part series, but I found another GMATPrep® problem (from the free tests) covering this topic, so here you go:

“A set of 15 different integers has a median of 25 and a range of 25. What is the greatest possible integer that could be in this set?

“(A) 32

“(B) 37

“(C) 40

“(D) 43

“(E) 50”

Here’s the general process for answering quant questions—a process designed to make sure that you understand what’s going on and come up with the best plan before you dive in and solve:

gmat1

Fifteen integers…that’s a little annoying because I don’t literally want to draw 15 blanks for 15 numbers. How can I shortcut this while still making sure that I’m not missing anything or causing myself to make a careless mistake?

Hmm. I could just work backwards: start from the answers and see what works. In this case, I’d want to start with answer (E), 50, since the problem asks for the greatest possible integer.
Read more