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How to Find Any Assumption in GMAT Critical Reasoning

Hey GMATters,

This post is 3200 words (nineteen flippin’ pages, yo). Want a PDF instead? Grab one here:

Critical Reasoning is a tricky subject, no doubt about it.

First, you need to learn to break apart the arguments.

Second, you need to be able to eliminate the objectively incorrect answers (that’s a subject for another guide).

While if you’re going for quick effect, you can jump to answer elimination. This certainly do more damage more quickly.

However, let’s start by addressing…

How to Break Apart Arguments

It’s all about Fact vs. Assumption vs. Conclusion. 
Generally, a GMAT-style argument will be in the following form:

1)  Premise (fact or assumption) 

2)  Premise (fact or assumption) 

3) Conclusion

Ultimately, this comes from the fact that the GMAT deals in inductive logic rather than deductive logic.


Important Detour: Inductive vs. Deductive Logic

Let’s do this quickly: you’ll need to know the terminology to proceed, so let’s address what Deductive and Inductive logic are.

Deductive Logic is straightforward organization of information.

Most of us know “deductive logic” from Sherlock Holmes’ dubious claims that his detective work was “deduction.”

We’ll leave it at that, since Holmes’ claim is as technically accurate as Alanis Morrissette’s definition of “irony.”

In other words, Deductive Logic is like an Algebra problem: all of the stuff is already there on the page; you’re just reorganizing to solve for X. There is no new information created.

You’re simply rearranging what is there in a new, more convenient form.


Inductive Logic is inferential: it requires a guess (and a test).

Inductive Logic works from empirical information, recognizes patterns, and makes an “educated guess” based on the information provided.

This guess creates new information.

Crucial: a computer is not capable of inductive logic.

Inductive logic can be best described as “an educated guess.” That is, since the Sun has risen every day for the past six billion years, I induce that the sun will rise tomorrow.

Of course it is possible—although exceptionally unlikely—that the Sun will not rise tomorrow: perhaps someone pushes that Giant Red Button while we’re all asleep and blows the Earth right out of its orbit.

Wait–how does Amazon know what I want to buy next?

Permit me a little correction: Amazon does not “know what you want to buy”; rather, based on your previous preferences and shitloads of data from literally billions of other purchases, it’s actually using statistical likelihood to put things in front of you that “you might like.” If it gets it right, you think it’s guessing well.

We won’t bother with getting into details about how using statistical likelihood differs from induction, but let’s note one important thing—you probably guessed already—statistical likelihood is deductive.

In short, computers with complicated-enough deductive systems try to approximate Inductive Logic, which is a reductive-but-effective way to state the main goal of Artificial Intelligence research. As soon as AI researchers succeed in creating a true Inductive Computer, we’ll all be fighting Skynet together.

Logical Leaps

The ultimate point of Inductive Logic is that there is a logical leap involved. We have to make the educated guess—the assumption—that because something has repeatedly been true that it will continue to be true.

That leap can be realistic, as in our previous example, or it can be completely insane (just ask people who think that Elvis and Tupac are still alive).

However, the GMAT tends to find situations where the leap seems more reasonable than it really is: that is, the argument’s leap “seems OK,” but it often still allows circumstances where the facts can be true yet the conclusion is still false.

(Notice how I keep repeating that last bit?)

What is a fact?

A fact is something that is objective and measurable. That is, a fact is something that you can take a photograph of, write down, place in an Excel spreadsheet, or otherwise record.

What a fact is not: an assumption, a conclusion, or a claim. That is, it is something that cannot be disputed unless proven untrue.

What is an assumption?

An assumption is a nebulous concept—at its most basic, you can think of it as something that “holds facts together.”

Another way to think about it is that facts themselves are like carved pieces of wood that make a chair.

Now the better the woodcarver has made the pieces, the better they fit together.

That’s not to say that there will be no spaces—even in the best-made furniture, there will be spaces at some level.

However, a great craftsman (or craftswoman!) can make a chair without using any glue at all—simply because these pieces fit together so snugly, they make a sturdy chair that can support a huge amount of weight.

An assumption, on the other hand, is like the glue. When the chair pieces are poorly carved, the glue is necessary to hold it together.

If the pieces don’t really fit together and there is a lot of space that needs glue, the chair doesn’t support much weight at all.

In fact, the more glue there is for a given number of pieces, the less weight the chair will hold.

Arguments work like this: the more snugly facts fit together, the less room there is for misinterpretation or false conclusions.

In other words, the closer-fit the facts are, the sturdier the arguments!

In other other words, the broader the assumption in an argument, the weaker the argument.

To paraphrase that dumbass teacher you had in high school (you know which one I’m talking about): “When you assume, you make an ASS out of U and ME.”


But what if there aren’t enough facts?

This leads us to my favorite GMAT logic analogy: conspiracy theory.

Philosopher Robert Anton Wilson often suggested the study of conspiracy theory as a means to improve one’s logic.

That’s not learning to believe in crazy-ass ideas, but rather as an exercise in skepticism. In other words, it helps us define how much we actually do and do not know.

Conspiracy theories arise from situations where we have a limited number of facts.

That is, there simply aren’t enough pieces to the chair to make it stand on its own, so it needs quite a lot of glue!

Clever conspiracy theorists are able to implicate UFOs, Elvis, or even elves in the JFK assassination or Kurt Cobain’s suicide. Why?

Because there are still unanswered questions. There aren’t enough facts available to lead to a definitive conclusion.

What we take as a “definitive conclusion” is no more “fact” than the ravings of some lunatic standing on a soap box on the streetcorner.

What does an acceptable story have that a nutbag story doesn’t have?

Well, like it or not, it just “seems more reasonable.” Does that make it more true? Does that make it deductively true? Absolutely, positively, NO.

Remember, any story has room for misinterpretation. Don’t let it hurt your brain too much, but we make a lot of guesses to keep things running smoothly in life.

For example, when I order a coffee in an English-speaking country, I tend to speak English. However, I speak French sufficiently well to order my coffee in French. It’s even possible that the barista also speaks French.

If both of those facts were true, I could potentially order in French and have the order communicated appropriately. Yet, realistically, if I don’t know the barista speaks French—and even if I do—there’s no reason to assume I won’t order in English.

After all, we’re in an English-speaking country. The general background language would be a Reasonable Assumption.

What is a Reasonable Assumption?

A Reasonable Assumption is effectively a situation where the assumption is treated as a fact because there are so bloody few exceptions that we might as well say those exceptions simply don’t exist.

Unfortunately, as you get better at Critical Reasoning, you’ll butt up against what the GMAT decides is “reasonable.” It’s very likely that as your logic gets sharper, you’ll start to cut just a bit too fine.

In other words, you’ll start to see assumptions that the GMAT considers “reasonable.” It’s only natural, because (in my own arrogant opinion) the test-writers just don’t think all that carefully about the distinction between Fact and Assumption and they more or less consider Reasonable Assumptions to be facts. So it goes…

My advice: do as many OFFICIAL GMAC[1] Critical Reasoning questions as possible.

When you cut too fine, you’ll always be choosing between the Almost Correct answer and the Correct answer. Take the time to define—in writing (say two or three sentences)—why the book’s answer is correct and your answer is incorrect.

After 50-75 questions, you’ll begin to understand, intuitively, where the testwriters draw their lines for what a Reasonable Assumption entails.

But Why Again with the Conspiracy Theories? You crazy.

Be that as it may, let’s focus. Put your phone away and listen.

To answer the question: it’s often useful to think of the wacky, “out there” scenarios in GMAT questions because this tests the boundaries of the logic that the test-writers have used.

Remember, a good argument leads directly to a particular conclusion. If it allows for any deviance, seemingly crazy or not, it is not an acceptable argument.

Aristotle has a lot to answer for.

The GMAT knows this, and loves to capitalize on it.

Most of the logical mistakes that we make in Critical Reasoning can be traced back to one thing, which has its roots in Aristotle’s work 2300 years ago.

Let’s look at Aristotle’s argument in short:

1)   The world has an inherent, objective structure outside of what we perceive.

2)   The human mind is able to take particulars—that is, what we perceive—and generalize based on these.

3)   We are able to attain knowledge of universal truths by generalizing based on these particulars.

Seem reasonable? While many thousands of volumes have been written on the problem with each of these statements, the GMAT is really only concerned with a tiny bit of this argument: the relationship between parts 2) and 3).

In short, in Critical Reasoning questions, we are given certain statements that are presented as fact. We are asked to generalize based on these statements.

However, it is possible that our generalizing is somehow flawed: are we legitimately always reaching universal truths? Hardly.

A classic example would be the old “correlation vs. causation” argument. That is, just because two things happen at the same time does not necessarily mean that one of these things causes the other—or, for that matter, that they are even related in the first place.

Consider this example:

Most vandalism in Town X occurs in the daytime. On any given day, up to 5% of teenagers in Town X are absent from school. Therefore, the teenagers who are skipping school are responsible for this vandalism.

If you see the problem here, great.

While it’s not necessarily untrue that the teenagers are causing the vandalism, it’s certainly not always the case. Think about it: is there possibly, just maybe, someone else who might be responsible? Could teenagers be absent for legitimate reasons such as illness?

Therefore, it’s pretty clear that we’re not always reaching “universal truths” by linking these facts. That’s not to say that we’re always wrong, but we need a more effective way to figure out when we are.

That’s the whole point of the Critical Reasoning section on the GMAT—we need to test the arguments to make sure that they actually hold water!

The best method to do this is found here… in the missing section of this blog post! Thanks TopMBA!

(of course you could just download the PDF for your convenience…)



By negating the conclusion, it immediately becomes a lot simpler to be able to identify our invalid Assumption.

Another word for it would be The Counterexample.

In fact, you may have heard of this, and sometimes the Counterexample comes to you without trying. At a certain level of preparation, this should begin to happen more and more.

(That’s a good thing!)

However, whether we like it or not, that’s an intuitive method.

The worst problem with the GMAT is that intuition is at once our best friend but it also tends to be the first thing to disappear when Stress rears its ugly head.

That’s the whole point of applying Reduction to Absurdity!

Thank Aristotle.

Our friend from Antiquity has absolved himself for his Crimes of Induction by giving us the tool to crack open bad arguments.

Next time you’re stuck, just remember the absurd (and give a hat tip to old Artistotle): if the conclusion and its negation are both possible, this argument isn’t going to fly.

Remember: it doesn’t have to be hard.

Enjoy this guide? Check out more at, including free guides and information on how to work with Rowan directly!


[1] If you’re doing non-Official questions, it’s your funeral. How are you going to be able to tell the difference between you not seeing appropriate logic and the writer of the question just being an idiot? Official questions are solid and extremely well-edited. Use them.


Whew! You’re done! Want to refer back to this How to Find Any Assumption in Critical Reasoning Guide at your convenience? Get a PDF copy here:

How to Apply Strategy to Beat GMAT Quant — MyGuru Guest Post

Hi GMATters,

This is a guest blog post from our friend Mark Skoskiewicz of Chicago-based Test Prep service MyGuru.

Want a full PDF of this guide? Click here:


GMAT Math and the Importance of Strategy 

To excel on the GMAT, mastering core underlying mathematical concepts and skills is critical.  The key to a 700+ score on the GMAT is certainly not “tips and tricks.”

At the same time, I can’t reinforce strongly enough that the GMAT is not a math test.

If you approach it that way, you will score below (likely far below) your potential score, whatever your level of underlying math knowledge happens to be.

Here are two key reasons why GMAT quant is best not thought of as a “math test:”

  1. You are often not asked to arrive at a 100% correct answer. Something that is about or approximately true is good enough.
  2. You get credit for choosing the right answer, not for demonstrating any given approach or method. You don’t get partial credit for showing your work and having been on the right track to the correct answer.

Keep in mind that the math covered does not typically go beyond grade 9 or 10 in the U.S. education system. So, you’re looking at algebra 2, geometry, and trigonometry. There are some topics, like probability or number theory, that violate this rule because many U.S. students learn these topics a little later (and sometimes not at all), but the basic idea is that the math itself is 9th or 10th grade in difficultly level.

That said, you are asked to apply your math knowledge creatively and use heavy doses of critical thinking. If you don’t internalize the two points above, you’ll find yourself trying to mathematically solve certain questions, spending a long time on what could be an easy question, and ultimately scoring well below your potential.

So, what is the right way to think about the GMAT section? If it’s not a math test, what is it?

It’s a test of logic, critical thinking, and strategy.

The tricky thing however is that the line between “tips and tricks” and “strategy” is sometimes not that thick. What may look like a “trick” to solving a problem is much better thought of as the application of a strategy that does rely on some core underling math knowledge, but which doesn’t treat the problem like a math test.

Let’s explore this idea with an example.

Thinking about GMAT Quant as a test of Logic and Strategy: An Example using Square Roots

Observe the question below:

A common, but far less than ideal, way to approach this question is to begin answering a math question that has to do with square roots. If you do this, you might start by recognizing that the sqrt (ab) = sqrt(a) * sqrt (b).

So, sqrt(80)  = sqrt(20) * sqrt (4). That’s 2 * sqrt(20), which could then become 2 * sqrt(4) * sqrt (5). So, now you’re left with 2 *2 * sqrt (5), or [4 * sqrt (5)] + sqrt (125).

If you apply the same math to the sqrt (125), you end up with sqrt (25) * sqrt (5), or 5 * sqrt(5).

Now, you are left with [4 * sqrt (5)] + [5 * sqrt(5)].

First of all, by this point, you’ve spent a fair amount of time.

But let’s continue. A common step at this point is to say, ah! One of the answer choices is 20 * sqrt (5). That what my equation above seems to reduce to. So, to save time, since it seems pretty obvious what the answer is at this point, you choose B.

But are you correct?

Well, no, you aren’t. If you stop focusing on the mathematical rules for square roots and manipulation of the equation, you can see estimate that the square root of 5 is something close to 2.5. So, [4 * 2.5] + [5 * 2.5] is going to equal something close to 20. But, 20 * sqrt (5) will equal something close to 50. So, that can’t be right.

Now what do you do?

Here is another approach to this problem. Instead of starting with the math, apply the strategy of seeing if you can make a slight modification to the problem to work with whole numbers instead of fractions or decimals or square roots.

So, consider looking at the problem as something close to the square root of 81 plus the square root of 121, instead of 80 and 125. Now, you can quickly answer the question. That’s 9 + 11 = 20.

Now you can look at the problem this way –

Think about how long you’ve taken so far with this approach. We are talking seconds of your time so far. And you are extremely close to getting to the right answer, because take a look at the answer choices.

You can immediately see that choices B. and C. and E. are much too large, and clearly are wrong.  Personally, D gave me a slight pause, but not too much trouble.

I know for sure and very quickly that 12 * 12 = 144.  I was somewhat confident just by thinking about how the math would work as I started plugging in numbers above 12 that I would reach 200 well before 20. Indeed, 15 * 15 = 225, so D is too low.

So, the answer is A.

And, if after realizing you needed an answer choice that was close to 20, you had simply started estimating top to bottom, you would have landed on A. as the correct answer right away.

All in all, this second approach gets you to the correct answer with very limited math knowledge. Instead, you think critically, apply some simple strategies (i.e., the strategy of turning awkward numbers into whole numbers you can more easily work with, and then the strategy of the process of elimination) and do some simple calculation.

I always find this problem to be a great example of how critical thinking and problem solving is fundamental to GMAT success. Did you need to know a math concept to answer this correctly?

Kind of. You had to know what a square root was, but you didn’t really even have to know how to manipulate and break them down into components.

Were you well served by simply turning it into a math problem and working out the answer? No. Instead, you can modify the problem slightly, eliminate obviously incorrect answers, and quickly and with confidence arrive at the right answer.

Many GMAT problems can be approached “strategically” like this.

Like what you’ve read? Check out MyGuru’s online GMAT Tutoring here!

Want a full PDF of this guide? Click here:

The Ultimate Guide to Picking a Private GMAT Tutor

Hey GMATters,

This post is 2500 words long! Want a PDF instead? Get it here:

Picking a private GMAT Tutor is a difficult and costly decision. These tutors charge tremendous amounts of money that you, the client, intend to exchange for GMAT success.

In other words, you are renting their brain to download its contents. How easy that is depends on a number of different factors.

This guide is designed to help you find the right tutor for you (hint: it’s probably not me because I’m too damn busy).

1) Qualifications

It might seem pretty obvious that you want your private GMAT tutor to have a stellar GMAT score.

This can be a fatal mistake.

While a mid-700s GMAT score is essential, a high score does not make someone a good teacher. A 770-scorer will not inherently teach you better than a 740-scorer. Sorry.

What do I look for?

Quite simply, teaching experience. GMAT is a complicated subject and your private tutor needs to be someone with a good few years (3-5 minimum) of experience teaching other people, reading people’s needs, and understanding how to communicate most effectively with students.

This doesn’t have to be experience teaching GMAT—it could be anything from tutoring while at university to spending a couple of years in the trenches as a high school teacher.

If you find someone lacking actual teaching experience, it’s likely a cowboy who just recently got a decent score and wants to make beer money.

Run–don’t walk–away.

What’s a decent score for a private GMAT tutor?

As schools become more selective, higher scores have become more important.

In 11+ years of experience as a GMAT tutor, I’ve met excellent GMAT tutors who scored anywhere from 720 to 780.

Look at it this way:

One in particular took a few years and ratcheted his score from 720 to 770, ultimately getting a free ride at a very reputable UK business school.

This is actually a good thing: hard work and persistence are qualities you are looking for in a private GMAT tutor!

That’s actually exactly how business schools look at GMAT scores. It’s not necessarily “the higher the better” for these schools. They are much more interested in how someone fits into the dynamic of the incoming class.

Someone able to score a 760+ is not necessarily a “well-rounded” person and might just be the old, fabled “brain on a stick.”

The question is not whether this person knows how to score high on the GMAT.

The question is: “can this person effectively teach me how to score high on the GMAT?”

With every rule comes an exception (especially on the GMAT!): two of my colleagues in London are 780-scorers. They both come from extensive experience as Secondary (high school) teachers. I couldn’t recommend them higher as private GMAT tutors.

Check them out here:

Chuck Dreyer:
Philip Linnell:

This guy says he got an 800!

Statistically speaking it is almost certain that he is lying.

If approximately 30 people out of the roughly 250,000 who take the GMAT every year get an 800, the odds that your dude here is one of them are sow low that I would invariably ask to see an OFFICIAL score report (the one on watermarked paper).

This guy says he got 800 three times!

Did he? That’s amazing. By the way, I have a bridge to sell you…

Has your private GMAT tutor taught for agencies?

Most have at some point or another. This is particularly useful because that means your tutor will have classroom experience.

If balancing the demands and queries of 12-20 people at once is ‘Nam, then teaching a dedicated, receptive private GMAT student is tug-of-war at a 4-year-old’s birthday party.

Is your private GMAT tutor dedicating at least half-time to GMAT tutoring?

Working as a private GMAT tutor often pays well enough that it is often the tutor’s primary paying gig. That benefits you because it means that the tutor has the time and headspace to devote to your particular concerns.

Why? Usually the tutor is a writer or a musician or is working unpaid on a start-up.

If your tutor, say, works at a bank and only tutors at night I would be suspicious. How do you know the lesson won’t be cancelled the next time she has to pull an all-nighter? How do you know she’s not thinking about office politics rather than your question about Combinations?

Buy her a pint and pick her brain, but don’t spend hundreds of dollars per hour on her.

2) Curriculum

Does your GMAT tutor have some sort of curriculum in place? Can he describe exactly what material he’s going to guide you through in some sort of reasonable detail?

That is, can he provide some sort of realistic roadmap for how to raise your score given your situation?
This can be told over the phone.

Don’t deal with someone who can’t pitch you properly on the phone. He won’t be able to communicate effectively with you in private, either.

This brings us to the next point.

3) Materials

Don’t work with anyone using “big box retailer” books. They start with B, K, P, and V. I think you’ll be able to figure it out from there.

Of course there is yet again an exception that proves the rule:

–Manhattan GMAT books are excellent

–Jeff Sackmann’s GMAT Hacks books are excellent

However, there is a caveat: all GMAT questions are not created equal. GMAT questions are incredibly precise little machines—written in a very specific style, which you need to learn to score well!–any question that is not an Official question is not helping you wrap your brain around that style.

Recognition of the Official style and comfort with it is the only way you’ll ever score well on the GMAT.

In short: make sure that your private GMAT tutor backs up Manhattan or other materials with Official GMAT questions.

These can be from the Official Guides (tutors should have the last few editions available for perusal), from the Exam Packs 1 and 2 available on, or the Paper Tests also available on

Furthermore, and also have resources of compiled Official questions that can be used (often they require editing since they’ve been compiled by non- native English speakers, but they’re usable as-is).

A note on Official materials

The explanations that GMAC commissions for their Official materials are quite poor. If your tutor relies on those explanations, I would be worried.

Using proprietary materials – did your private GMAT tutor write his or her own questions?

In short: it’s not a reason to choose a tutor.

Some tutors write their own material and some don’t. It’s not necessarily a bad thing, but it’s not any sort of advantage.
The quality of the question writing varies, but let’s look at it from a different perspective: writing GMAT questions takes a lot more time than teaching GMAT.

The actual writers of the test make less than good private GMAT tutors—sometimes significantly less.

From a practical standpoint, it’s unlikely that a tutor would spend his time writing questions when he could be tutoring. It’s very likely that a tutor who claims to have written his own questions will have farmed them out to a student who works for cheap.

That means the questions are probably not great. Just saying.

Using computer-based systems

Manhattan’s online exams and question banks are excellent, providing great feedback and explanations. They do not, of course, provide Official questions.

Magoosh is widely considered the best bang for the buck when it comes to online GMAT preparation. Its questions aren’t as hard as Manhattan, but their style is much closer to Official questions.

Avoid others, especially “adaptive” courses that do not let you pick your own question topics (that one starts with an E). Freedom to choose what to study is essential to learn effectively.

4) Bedside Manner

One of the most important parts of your relationship with your private GMAT tutor is whether you get along.

This isn’t about shared politics or whether you’d even want to hang out with this person on any sort of social terms.

Rather, is this someone you can develop a communication, a rapport, with?

A lot of this can be determined over the phone. Speak directly to your prospective tutor. Tell the tutor a couple of things you’re having problems with.

See if she offers you any free advice. Is she able to give you an example that makes sense easily, without a pen and paper in front of you? A few nuggets of wisdom cost nothing.

If the GMAT tutor is cagey and tries to make you pay before dispensing any useful information, this is a bad sign.

A note on trial sessions

Any private GMAT tutor will have a policy regarding trial sessions. Some require you to pay for any session you book, while some will offer a one- or two-hour session as a trial.

My personal policy is to offer the first hour as paid with a money-back guarantee. The lesson costs up-front, but if the student is dissatisfied he or she gets the money back.

Strict policies are a response to the many “tourists” who will do trial sessions with every private GMAT tutor in town and try to get a full set of lessons that way.

Don’t believe that happens? Remind me not to tell you about the Easter Bunny.

In short, “trial” or “no trial” is NOT a reason to choose one tutor over another.

Does your prospective tutor take on anyone and everyone?

Private GMAT tutors are often flooded with work. Luckily we have the luxury of choosing our clients.

It is not in the interest of a tutor to take on a client with whom she doesn’t have good rapport or who will almost certainly prove to be a drain or otherwise a pain in the ass.

Your GMAT tutor needs to be firing on all cylinders or you’re not getting your money’s worth. As a client, it is not your responsibility to deal with the bullshit that bad clients can put your tutor through.

The important thing to note here is that your tutor must have strict boundaries and be able to say “no” to potentially bad clients.

The way to tell a tutor’s policy on this is simple. It’s likely on his or her website, but if not simply ask “do you ever refuse to teach anyone?”

Any tutor worth his or her salt will tell you YES and perhaps even give an example.

Does the tutor sound desperate?

Again, private GMAT tutors—especially in major metropolitan areas–rarely suffer for a lack of work.

If this person is really trying painfully hard to close a sale, there’s probably a reason.

Look for the tutor who is confident enough in her work not to need your custom.

Does the tutor claim to be able to work miracles?

Be wary of anyone who claims to get a 420 to a 700 in three weeks. Just saying.

However, if a tutor tells you he CAN’T work miracles but that he can guide you and it’s all down to your hard work, you have likely found a winner.

Is the tutor willing to recommend other tutors?

If he’s being precious about you as a lead, forget him. That’s just desperation all over again.

If he is happy to offer trusted colleagues—other folks in the game within your region—then you have found someone secure in his abilities.

Does this tutor say he or she is “the best?” Does this tutor slag off other tutors to you?

Is that really necessary? Maybe she needs to shut the hell up. There are plenty of charlatans out there, as I’m sure you’re able to tell by now. I still won’t name names.

Whether this tutor actually is “the best”—best out of what? The Westminster Dog Show?–should be obvious from testimonials.

If statements like this don’t turn you off immediately, ask for references from previous clients (at least three).

Does this tutor watch the clock relentlessly during lessons?

If he’s staring at his watch, chomping at the bit to let you out at 1:57 when the lesson actually ends at 2:00, I’d be worried.

If you find someone not willing or ready to take a few extra minutes to wrap things up, chat, and give you some guidance on homework, avoid this person.

5) Price

This depends entirely on location.

Remember that online private GMAT tutors can charge whatever they choose—they are not bound to clients from any particular pricing ecosystem. Many of these actually tend toward New York prices, which tend to be the highest worldwide.

However, in any case this tutor should charge significantly less than what you would pay through an agency.

Figure out what the reasonable average is within your area. If you’re not in one of these areas, the price could easily be less.

London: £65-90/hr

New York City: $200-300/hr

Los Angeles: $150/hr

Sydney: $130-150/hr

Continent (Paris, Frankfurt): €100-150/hr

Chicago: $75-125/hr

Can’t I find a good tutor for cheaper?

Eh, maybe. It’s not impossible but it’s not likely.

If you find someone working online from Kansas who’s charging $30/hr my first question would be what she’s doing in fucking Kansas.

I mean I’m from Kansas, but I don’t live there. Jeez, not even Dorothy actually stayed there.

More importantly, CAVEAT EMPTOR.

Buyer beware. If you find someone charging $40/hr in a place where $200/hr is normal, I would suggest you tend more toward the higher price.

Why do private GMAT tutors cost so much?

After all, someone needs to be able to justify herself at a high price. You want a private GMAT tutor who has the confidence to price herself at a point that proves her worth.

If she thinks she’s worth $40/hr, you’ll get tuition worth $40/hr. Is that going to get you a

Because the sky is blue.

(Ask a silly question…)

Look at it this way:

Business school is an investment. Arguably the most important part of that investment is the name of the school—the quality of the pedigree you will receive.

Ultimately, spending a couple grand on a private GMAT tutor can get your GMAT score up to a level that means you can go to a significantly better business school.

Getting a better pedigree will be worth incalculable amounts more AFTER THE FACT. If price is still an issue, please don’t call me. You’ll get what you pay for.

6) Conclusion

Hiring a private GMAT tutor can seem daunting. It doesn’t have to be. Talk to the person and ask questions.

An incredible amount of your potential relationship with this tutor will be totally evident from a 15-minute chat on the phone.

Make sure your tutor is someone trustworthy with whom you can easily develop rapport.

If in doubt of this, talk to the one who charges a couple of bucks more per hour. This often makes all the difference.

Good luck choosing a GMAT tutor, and as always, good luck on the exam!

PS Skimmed right to the bottom? Grab a PDF copy of the Ultimate Guide to Picking a GMAT Tutor here!

VIDEO: How to Cancel Variables in GMAT Data Sufficiency

Hi GMATters,

We’re all taught that “you need at least as many equations as you have variables.” In fact, that’s one of the first principles in a lot of GMAT texts.

The simple fact that it’s in the damn GMAT books is almost undoubtedly why tricky DS questions love to punk you by having a variable simply disappear as part of the structure of the question.

In short, when you reorganize the information given at the beginning of the question (and occasionally when you plug a Statement in–but not in this video), you’ll find that what you thought was a variably really just falls out.

Why was there a variable there in the first place if it wasn’t necessary?

Look, this is like a three-year-old asking “where the sun sets.” It begs a longer, philosophical discussion of a “placeholder variable,” but mercifully I won’t bother you with the details.

After all, this is GMAT-land, and getting the job done is more important than the dreaded “whys.”



PS Enjoying the videos? Support the channel with a “like” or subscribe on YouTube!

PPS I mean if you really do care to hear about placeholder variables, let me know and I’ll explain further. I’m geeky like that.

VIDEO: How to Cancel Variables in GMAT Data Sufficiency

Hi GMATters,

We’re all taught that “you need at least as many equations as you have variables.” In fact, that’s one of the first principles in a lot of GMAT texts.

The simple fact that it’s in the damn GMAT books is almost undoubtedly why tricky DS questions love to punk you by having a variable simply disappear as part of the structure of the question.

In short, when you reorganize the information given at the beginning of the question (and occasionally when you plug a Statement in–but not in this video), you’ll find that what you thought was a variably really just falls out.

Why was there a variable there in the first place if it wasn’t necessary?

Look, this is like a three-year-old asking “where the sun sets.” It begs a longer, philosophical discussion of a “placeholder variable,” but mercifully I won’t bother you with the details.

After all, this is GMAT-land, and getting the job done is more important than the dreaded “whys.”



PS Enjoying the videos? Support the channel with a “like” or subscribe on YouTube!

PPS I mean if you really do care to hear about placeholder variables, let me know and I’ll explain further. I’m geeky like that.

The Surprising Key to GMAT Success (hint: it doesn’t involve Probability)

Download this entire post as a PDF guide!

Get Used to Repeating Questions

“The secret is reps, reps, reps.” –Arnold Schwarzenegger


This guy knows what he’s doing.

It’s painfully common for me to hear a new GMAT student say “I’ve bought all the books and the courses and downloaded things from the bad place and I have 20,000 questions so I’ll never need to get bored and I’ll never have to repeat a question!”

This is a student who will not reach 700—at least not without a serious mindset shift.

It really doesn’t matter what you’ve read on the GMAT forums. Don’t get me wrong: the forums are a great resource for explanations, but they’re worse than a sewing circle for poisonous gossip about preparation strategy or judging the difficulty of questions.

Practice the Questions That You Get Wrong

Let’s be honest. If a person learns ALL of the questions in the Official Guide and can do ALL of them in an efficient way in two minutes or less without excess expenditure of energy, that person should be able to reach 650+ on the GMAT.

By the way, when I say “in an efficient way,” that VERY RARELY means “the way it’s done in the back of the book.” Word to the wise: OG explanations are “correct,” but they’re certainly not efficient.

The only realistic way to do this is to go through the Official Guide question-by-question, mark the questions in order of perceived difficulty, and then repeat the questions that you found difficult.

Over and over. Until they’re not difficult. If that takes five times, ten times, or more, so be it. If it takes getting the questions explained by a professional like me, so be it. Getting help will be an investment in your future.

The Rub is This

No one ever fucking does it. They don’t complete the Guides! They don’t repeat the questions!

I’m saying that with a grain of salt—700-level folks do—but that’s why they’re above 90th percentile!

As a note, the 650 number is a conservative estimate. It’s very likely that a person who really internalizes how to do all the questions in the three Official Guides would be able to reach a 700+.

However, there’s simply not a sufficient density of 700+ questions in the OGs to approximate the difficulty of the real exam situation.

Getting hit with 30 or so 700+ questions in a row is a feat and it’s something that top performers will ultimately have to practice in order to ensure good performance. Practice material from other sources is usually necessary simply to reach this density.

Why Should I Stick to One Book?

That’s not what I’m saying.

The Official Guide provides two key things: it gives a good scope of what you’re likely to see on the GMAT. It’s pretty much impossible that you’d find a concept on the real exam that you haven’t seen in one of the three Official Guides.

That’s nearly 1500 questions. If you know all of them and know them well, you’ll be fine.

As a note, when I say “concept,” I mean topics covered on the exam. The individual algorithms for the questions—that is, “the way to solve this particular question” can of course vary.

The key is to know the concepts well enough that you can improvise a little bit with the algorithm. You’ll be looking for the “best way” that you can find under the high-pressure exam circumstances.

But How Do I Do the Same Thing Over and Over and Not GO COMPLETELY MENTAL?

Don't have a bathyscape? Just plug your nose and dive.

Don’t have a bathyscape? Just plug your nose and dive.

Simple: Go Deep, Not Wide


Here’s a nice little trick for dealing with repetition.

I can’t stress enough the importance of keeping a log of all the Official Guide questions. I’d suggest creating a log where you have a space to rate the questions from 1 to 5 in order of difficulty.

The ratings are as follows:

1: I can do this next time with zero problem
2: Pretty confident, but not 100%
3: Maybe it was correct, maybe not. Still not sure I could do it next time.
4: It was wrong, but I think I understand why.
5: Help!

Once you have all the questions in the book logged and rated 1-5, you know that you’re ready to begin the repetition phase.

How to Repeat Questions

–Ignore the 1s.

–Take the 2s and do them a couple more times (repeat every 2-3 days) until they become 1s.

–Take the 3s and do them a couple more times (repeat every 2-3 days) until they become 2s.

–Take the 4s and do them a few more times (repeat every 2-3 days) until they become 3s.

–Take the 5s and get some help if necessary and do them as many times as necessary until they become 4s, then 3s, etc.

Rinse and Repeat. Once all the questions are 1s and 2s you’ll be pretty safe to take the exam.

But I Remember the Answer is D!

Awesome! Now can you go up to the blackboard and show me how to get there, step-by-step, in a way that gets you there in under two minutes?

Yeah, I didn’t think so. Now sit down and shut up.

Look, I’ve been teaching GMAT preparation for more than 11 years. I’ve forgotten more about this test than most people will ever learn.

Even now, I’ll forget the exact algorithm (not concept) for certain questions. It might take me a bit of exploratory work to figure out the simplest way.

Long story short, it’s about the process of solving, not about the actual answer choice. Memorizing that the answer was D will get you absolutely nowhere. Memorizing its basic question type and the general technique for tackling this question will get you to 700.

What About When I Reach 700?

Are you there yet? I didn’t think so.

Still, because I’m nice, in a future e-mail I’ll you a few books to crack ONLY when you’ve finished with the Official Guides. These books give a better idea of the process for solving difficult questions—honestly, that is significantly more important than the extra questions themselves.

I personally recommend these resources because I’ve personally used them at various times in my career. And for anything not on this list? Ignore it.

That’s why I recommend using any additional materials as textbooks ONLY–that is, learn techniques and principles from them by reading the explanations. DO NOT USE THEM AS QUESTION BANKS.

You ARE reading the explanations and not simply using the practice questions, right?

I only say this because it was as if the scales lifted from my eyes on the day that I realized there was writing about HOW to do questions in my Physics textbooks—it wasn’t just random-ass questions in the back that I had no idea how to do.

These GMAT texts are no different. They are the textbooks written by experts—their techniques and methods for solving questions will help you even if the questions themselves aren’t as precise as Official Guide questions.

Any Questions? Comments? Just reply to this e-mail!

Download the entire post as a PDF guide!

PS I’m looking for specific questions to create video explanations for, so if any come to mind just reply to this e-mail and I’ll create and post an explanation at .


When “Always True” Isn’t True on the GMAT

Sentence Correction is at once one of the most objective, “quant-like” sections of the GMAT Verbal, to paraphrase Ron Purewal from Manhattan. What Ron is talking about is that there are a lot of pretty objective rules that you can apply—things that will work a huge majority of the time.

In my own practice, I call these “95% Rules.”

What’s a 95% Rule?

There are quite a number on the GMAT. In fact, it would be almost every “rule” rule within the Sentence Correction section.

In short, these are situations where one objective statement will work the overwhelming majority of the time, but in certain contexts you’ll find that it’s OK to use a different one.

The way I look at these is to say, “I’m going to use the 95% Rule to eliminate three of the potential answer choices.”

This leaves me with one or two remaining. In the case that one of these remaining answers is pretty clearly correct I don’t feel bad about choosing it.

In the case that both of the remaining answers are objectively incorrect, I’ll have to step back and wonder what’s gone funny here.

If you have to guess, go with the 95%!

If you have to guess, go with the 95%!

Why doesn’t it work all the time?

Simple: these are style errors and not grammar errors. They don’t sound great but there are circumstances where you’re forced to go with odd style to make the grammar work correctly.

More importantly, perhaps, you’ll find situations where the other four choices are just objectively incorrect and you’ll have to go with bad style even if you don’t want to.

Those suck.

Putting it into practice

One of the most classic 95% Rules on the GMAT is use of the word “being.”

An incredibly huge amount of the time, any sentence with the word “being” can be considered incorrect. Really—just go through and throw out any potential answer that uses the word “being” except after a preposition (“of being,” “by being,” “for being,” etc. are OK).


It’s because “being” is the gerund form of “to be.” It is “the act of being,” the same way that “running” is the verb form of “to run” and means “the act of running.”

Because “the act of being” is really the same thing as existing, if anything “is,” then it “is being.” That means it’s redundant in almost every case.

Too much philosophy? Just remember to throw the damn word out.

This works well—until it doesn’t

This is question 100 in the Official Guide for GMAT Review 2015 Edition and question 110 in the Official Guide for GMAT Review 2016 Edition. The correct answer is printed below in its entirety.

Being heavily committed to a course of action, especially one that has worked in the past, is likely to make an executive miss signs of incipient trouble or misinterpret them when they do appear.

So how do we know what’s happening here? It’s an ugly sentence, no question. Would it be better to rewrite it as “Heavy commitment to a course of action…?” No doubt. However, that’s not one of the answer choices. All of the other choices are grammatically incorrect.

Remember that “being” is a redundancy error—that’s style and not grammar—if we have an objective grammar problem, it will be “more disqualifying” than a style issue.

Head hurting yet?

Let’s take a look at a different example.

Our 95% Rule is that when speaking about amounts of money, we need to say that, for example, “200 dollars is on the table.” Basically in any case we would use “is.”

It’s pretty simple: “200 dollars is on the table” would indicate 200 dollars in any form. That is, it could be a check, poker chips, Euros ready for exchange, etc. If we were to say “200 dollars are on the table,” we would be implying 200 single dollar bills. Generally this is not what we want to do.

Nevertheless, it’s not objectively grammatically incorrect to use the “200 dollars are” form… This implies that of course situations will arise where we see this as correct. They’re simply less common than the alternative.

Let’s look at another example from the OG: this is Diagnostic Test question 36 in The Official Guide for GMAT Review 2015 and The Official Guide for GMAT Review 2016.

New data from United States Forest Service ecologists show that for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel, seven dollars are saved that would have been spent on extinguishing big fires.

Notice that we’re using the “are.” Why? Well, the other four choices are of course objectively wrong.

Cash or check?

Cash or check?

Nevertheless, it sort of makes sense to say “seven dollars are saved” because seven dollars isn’t really a huge amount of money. We’re inflating its importance by using “are” and thinking about seven individual units rather than one unit of seven that seems somewhat puny.

Whew. Enough examples for today?

Attack these problems and more at your leisure.

Check out my Complete GMAT Grammar Basics Part I for a dive deep into the waters of proper GMAT grammar.

This course will teach you all the fine distinctions you’ll need to master GMAT grammar and stop faking it, complete with multiple examples.

Part II will come through within a month’s time, addressing finer grammar points that some consider “style” rather than proper structural grammar. It will also include extensive suggestions on how to apply your new learnings.

Check out Complete GMAT Grammar Basics Part I today. Comes with a free download of the #1 Amazon Bestseller Last Minute GMAT Grammar!

Part II will come with a free download of the Last Minute GMAT Grammar audiobook so that you can review your grammar concepts on the train, in the car, or while exercising!

What are you waiting for? Check out the Complete GMAT Sentence Correction Course Part I today!

When “Fake It Til You Make It” doesn’t work

What does that term mean and how does it apply to the GMAT?

In fact, it’s pretty much a guiding principle in life and business. If you’ve ever learned how to do anything well, chances are you did apply a little bit of this idea.

To learn a native language, you use patterns that you think will work. Then a parent or a teacher tells you that you’re saying something incorrectly, so you fix it mid-stream.

You try things out. What works stays and what doesn’t goes. It’s that simple. The point, though, is that you’re trying—you’re applying what limited knowledge you have—and learning by trial and error as you move forward.

Somehow, as adults, we seem to forget this.

Who's wearing the perfume?

Who’s wearing the perfume?

The way that we approach learning as adults seems to be much more along the lines of how someone learns a language as a student: learn all of the grammar rules and apply them precisely, making sure that we’re saying exactly what we’re trying to say with absolutely no errors.

Does this work? Well, for some people who have a “natural ability with languages” it does. These people can understand grammar very well and apply it in conversation very quickly.

The dirty truth, however, is that they’re spending a lot of time speaking the language and making mistakes. That’s how they become conversational. Basically, they’re approaching language learning from the “immersion” perspective.

They might not be doing it in front of the teacher, but very few people actually learn to speak without actually, you know, speaking. They just learn how to incorporate the new grammar rules because they have applied them and made the fundamental mistakes and have then moved on!

GMAT learning requires mistakes.

If you want to learn how to succeed on the GMAT, I’d suggest an approach that involves lots of faking it until you make it. Learn how to do the GMAT the way a child learns how to speak a language!

In fact, making every possible error would be a great way to learn—if you had the time and the inclination to study what you were doing wrong and to correct these errors.

In that case, what would happen is that you’d be able to see the underlying patterns on the test and be able to understand how to address these patterns when seeing a similar question in the future.

However we don’t have the luxury of 3-8 years of immersive learning—the way a child does to get a good grasp on a native language—to succeed on the GMAT. In a good scenario it’s six months, and often more like 4-6 weeks (PLEASE, PLEASE give yourself at least three months!).

Learning quickly requires faking it AND knowledge work.

So what can we do about this? Apply a program of faking it as well as study of the raw knowledge required.

This is most obvious with Quant concepts: if you don’t understand something, you study the concept and apply that concept until it makes good sense.

Where it breaks down is in the Sentence Correction section. GMAT testtakers almost all speak English well enough to “fake it,” but the problem is that the fluency required to succeed on the GMAT actually encourages people to do so.

That is, GMAT Sentence Correction questions assume that the testtaker speaks English really well—and speaking “really well” means being able to “read between the lines.”

This is the kiss of death in the Sentence Correction section.

Remember that structure is king in Sentence Correction and if you’re saying something that “makes sense” but isn’t written perfectly, then you need to make sure your Structure matches what you’re trying to say.

How can we do this?

The simplest way to do this is a little though experiment:

Let’s call it the “garbage in, garbage out” (or GIGO) test. GIGO is a test that computer programmers have used since the early days of programming (the term was coined by the US Internal Revenue Service in the 1960s).

Put simply, if you feed badly structured or corrupt information into a computer, the machine—unthinking—will spit out bad information. The computer can’t guess what you’re after.

It’s like putting the wrong number into a calculator: of course the damn answer will be wrong!

So if the structure of your sentence is something that suggests a meaning that is ambiguous or even distinctly different from what you specifically mean to say, then the computer will not understand the true meaning of what you INTEND to say.

Are you saying what you intend to say?

Have you figured it out yet?

Have you figured it out yet?

The test, therefore, is to consider each potential sentence as if it is being fed into an unthinking computer. Will the computer understand exactly what you mean to say or could it come up with a different, equally valid alternative?

Unless the sentence structure clearly transports EXACTLY what you’re trying to say—with no ambiguity—then it has failed GIGO and you need to pick another sentence.

How do we tell what sentences are correct?

Unfortunately this implies learning GMAT grammar very well. Unfortunately GMAT grammar doesn’t correspond 100% to any other grammar system you’ll find.

Are you confident that you know exactly what grammar the test expects? Haven’t seen a grammar textbook since grade school (or ever?).

The solution you’ve been waiting for.

The cure for these ills has arrived: check out my Complete GMAT Grammar Basics, Part I for a dive deep into the waters of proper GMAT grammar.

This course will teach you all the fine distinctions you’ll need to master GMAT grammar and stop faking it, complete with multiple examples.

Part II will come through within a month’s time, addressing finer grammar points that some consider “style” rather than proper structural grammar. It will also include extensive suggestions on how to apply your new learnings.

Check out Complete GMAT Grammar Basics Part I today. Comes with a free download of the #1 Amazon Bestseller Last Minute GMAT Grammar!

Part II will come with a free download of the Last Minute GMAT Grammar audiobook so that you can review your grammar concepts on the train, in the car, or while exercising!

What are you waiting for? Check out the Complete GMAT Grammar Basics Part I today!

Are You Making the Biggest Mistake in GMAT Verbal?

Let’s face it: you don’t know how to read for the GMAT.

But why would you? A good, solid education will teach you exactly how NOT to read for the GMAT.

Having trouble with the Reading Comprehension section of the exam is pretty much proof that you have a good degree!

If you're not reading from the computer screen, you're doing it wrong.

If you’re not reading from the computer screen, you’re doing it wrong.

What’s the problem?

Ultimately, the techniques that are useful in university-level research and reading are hardly the techniques that will be useful for this particular exam.

There are a very few things that the Reading Comprehension section asks you to do.

What are those things?

On the whole, you need the ability to zoom in and out of the passage.

First, you need to be able to define WHAT the passage is talking about, no more and no less. That is, if it’s talking about a particular mangrove tree in a particular swamp in Florida, it had better be about that particular tree! Not about branches on that tree (too narrow) or all mangrove trees (too broad).

This can be done VERY QUICKLY. That is, a lot faster than you might expect! I’d say somewhere between 30 seconds and two minutes for any passage.

This is similar to the SCOPE you may have heard about before.

you need the ability to break the passage into smaller, identifiable chunks (four or five per passage) and be able to determine what they have in common (hint: it’s the Purpose!).

Third, you need to be able to figure out what the point of all of these little chunks is when put into the perspective limited by the Scope.

This is the THEME or PURPOSE of the passage. Can you tell me what it is in one sentence? Then that’s not it.

One sentence is all it takes.

How can I define the purpose?

Another way to look at it is to assume that each passage has a PIVOT IDEA. That is, an idea that links the second half of the passage to the first half.

If you get that Pivot Idea, you have basically got the Purpose of the passage. If you still can’t do it in one sentence, it’s not good enough.

How can we tell what is adequate to answer the questions?

Look at the answer choices.

If the Scope is too broad or too narrow, eliminate it. If the language is too strict or severe (hint: “seems to be” would be better than “is always”), throw it out. If it doesn’t address the Purpose, throw it out.

How can we use structure to our advantage?

An old colleague used to tell students that any GMAT passage can be read in 30 seconds and all its questions answered with at least 80% accuracy.

While this may be true in principle, it speaks of an important distinction: 80% of the questions are structure-based questions, while 20% of the questions are detail-based.

The important thing is to learn the structure of the individual passage and furthermore to be able to identify where the DETAILS relevant to the detail questions lie.

Detail questions are of course based on the information that is clearly in the passage. You just have to uncover it. If you know where the details are and are careful of trap questions, you’re bound to get the answer correct!

It’s a game of balance.
Learn to read for structure rather than detail and you’re 80% there. The other 20% comes from taking things slowly and carefully.

Click HERE to arrange a

PS Are you reading properly for the GMAT?

PPS Do you know your WPM reading rate?

VIDEO Breakdown: An Easy Way to Gain Points in GMAT Quant

There are a few Quant topics on the GMAT that are much simpler than they seem.

Learning these topics will boost the hell out of your GMAT prep. Factoring, Counting Problems (Permutations and Combinations), Probability, Mixtures, and Venn Diagrams round out the list. Unfortunately, Percents and Rate Problems will always be hard–and this is coming from a Physics major!

So what distinguishes between easy and difficult questions on the GMAT? Counter-intuitively, questions that should be simple such as Percents and Rates will often be “made more difficult” by twisting them, GMAT-style. That is, they are over-complicated or given with missing information in odd places or just plain asked in the most intentionally-confusing way possible!

However, the questions that “set a higher bar” at the beginning–that is, the stuff you were less likely to see in high school–tend to be the easiest questions to answer correctly. The testwriters basically assume that because you had to learn it fresh for the GMAT that you must be worse at it. Therefore, they don’t put as much effort into making it intentionally confusing.

In other words, the question is thought to be confusing by its very nature, so it’s not twisted around and asked in that perverse GMAT-tricky style.

Let’s take a look at a “difficult” factoring question here:

Question text:

The integers A, B, C, and D shown on the number line above are all equally spaced. If C and D are equal to 5^12 and 5^13, respectively, then what is the value of A?

Factoring is like the gymnastics of the Quant section. If you’re flexible enough working with exponents (powers, indices–all the same thing), then you’ll see that when adding and subtracting different values such as 5^12 and 5^13, you can actually factor out numbers that AREN’T 5s!

This is a common trick on the GMAT and–for example in this problem–is a good way to eliminate 2 or 3 answers (here: A, B, and C can be safely ignored).

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