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

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

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

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

(A) 1/3

(B) 1/2

(C) 2/3

(D) 5/6

(E) 1

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

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

It’s a funny thing—folks get good at doing OG problems at their desks.  Then they take a practice CAT, with the clock on the monitor running down, like sands in the hourglass.  Suddenly they are seized by amphetamine psychosis.  Like NFL rookies, the big adjustment is to the speed of the game.  When you’re taking the test, if you can’t do it* in two to three minutes, you can’t do it.*  However, timing problems are an effect, not a cause.  People have timing problems because their math foundation sucks.  People have timing problems because they don’t get a good rephrasing.  People have timing problems because they don’t compare SC choices vertically.  People have timing problems because they don’t have the discipline to guess.  And so on.  All of these problems are fixable.  Like most GMAT issues, timing problems are the result of either a poor foundation or bad behavior.

Take foundation work. . .please—that’s a joke from your grandparents’ day.  When I say 7 times 13, you say 91.  Think of it as a rap.  When you see .625, you say 5/8.  Woot.  All seriousness aside, people waste 30 seconds a question in the quant because they don’t know their times tables or squares or the fractional decimal percentage equivalencies.  Or their algebra isn’t smooth and silky.  Think about how much time that uses up during the section.  How do you fix that?  How do you get to Carnegie Hall?  Practice, practice, practice.  That’s a New York joke—LA classes hate it.  You have to want it enough to do the work that you need to do.  That amount varies, person to person.

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Did you ever have one of those anal teachers in high school math or science who would take off points if you did not include the correct units? So an answer of 7 would only receive partial credit when the answer was 7 inches.  Although this practice likely seemed frustrating at the time, I hope to provide some method behind this madness “ or specifically how awareness of units can help you on the GMAT.

My appreciation of units first began during college. I was a chemistry major in college, and as part of my major I had to take physics.  The topics in physics never came naturally for me so I was always looking for little tricks that would lead me towards a correct answer.  One trick I found that was surprisingly effective was to just combine the numbers in the way such that the answer was in the appropriate units.  For example if the question asked for an acceleration (the rate at which speed is changing or the second derivative of distance for the calculus-inclined), I knew that acceleration is always in the form of units of distance / units of time^2 (e.g. meters/ seconds^2).  So unless I combined the numbers in a way that resulted in these units as the answer “ for example by dividing a speed in meters per second by a time in seconds “ I knew I had done something wrong.

Since units are not required on the GMAT, I find many students exclude them entirely from their note taking and calculations.  But keeping track of units, while it may cost a little time, can help lead you towards right answers and prevent you from doing illogical algebra.
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Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.

For every five hours of studying combinatorics-type questions, the average GMAT student increases their chances of being able to correctly answer a question type that is found only on the very difficult end of the GMAT spectrum. Meanwhile, the same student will have to compute hundreds of basic computations without the aid of a calculator. For students who know how to quickly do these computations, they are rewarded with extra minutes that can be spent double-checking their work and critically thinking about whether their answers make sense. As BenGMAT Franklin might say, a second saved is a second earned on the GMAT, but it doesn’t matter if those extra seconds come from being faster at doing combinatorics questions or quicker at computations. So check out these five math tricks, learn the ones that you like, and practice them daily to give yourself some extra time to finish off that 37th and final Quant question.

Note: like everything else on the GMAT, being able to do something and being able to do something QUICKLY are two different tasks. If you like any of the following math tricks, make sure you know it inside and out before you try using it during your test. Read more

I’ve been speaking with a lot of students recently who are really struggling with translation problems “ even when they can figure out how to translate, they end up taking way too much time on the problem.

So let’s try this GMATPrep problem; set your timer for 2 minutes and GO!

If Bob produces 36 or fewer items in a week, he is paid x dollars per item. If Bob produces more than 36 items in a week, he is paid x dollars per item for the first 36 items and [latex]1frac{1}{2}[/latex] times that amount for each additional item. How many items did Bob produce last week?

(1) Last week Bob was paid a total of $480 for the items that he produced that week.

(2) This week Bob produced 2 more items than last week and was paid a total of $510 for the items that he produced this week.

Ugh. Okay, obviously we’re going to have to translate, because we’ve got a story going on here. It also looks like there’s going to be some algebra involved. Let’s dig in.

I’m now Bob. (Put yourself in the story; that’ll make things a little bit easier.) I can make either 36 or fewer items in one week or more than 36 items. How am I going to get paid? For the first scenario, I can figure out my pay by multiplying the number of items by x. If I make exactly 36 items, I’ll get paid 36x. If I make 33 items, I’ll get paid 33x. Hmm. I guess I should assign a variable for the number of items I make; let’s call that N.

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After seeing quite a few Integrated Reasoning problems floating around out there, I’ve found that one of the toughest situations to deal with is when instead of providing a single solution, the GMAT constructs a world with multiple possible solutions and then asks you to pick something that works within those parameters. Let me show you an example:

—

x, y and z are positive integers. The sum of x and y is 40. The positive difference between y and z is 20.

In the table below, identify values for x and z that are together consistent with the information. Make only one selection in each column.

—

Found the answer yet? If not, I think I might know why: You’re trying to solve for y. The problem is, y could be almost any integer from 1 to 39, as long as you pick values for x and z that work. You could figure out x and z for every single value of y, but that’s a very time-consuming strategy! Without the answer choices, there are more than 50 different solutions to this problem. So what is a better strategy than trying to solve for y?

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September is the greatest month of the year. At some point in the not-so-distant future, my AC-unit will be able to finally power off after five straight months of keeping me inside, away from the Texas heat and the West Nile carrying mosquitos that the heat brought with it. But more importantly, September means that football is finally back. So with that in mind, here’s four lessons from the college football season for those of you who need help rationalizing your Saturday afternoon absence from your GMAT study place.

1)  Schedule the Cupcake Sections Early

Oregon hasn’t been spending the last three months preparing to face Arkansas State. And when September 1 rolls around, Oregon would prefer to pull its starters sometime early in the second half. A loss to an early season opponents would definitely hurt their BCS chances, but if the Ducks play half-decent football at the start of the season, they can focus on playing their best once Pac-12 teams start traveling to Eugene in late September.

For you, walking away from the test with a 2 on your AWA or IR section could be a bad thing when it comes time to apply to business school. But running up the score on your AWA won’t help your 200-800 score and you don’t want to exhaust your brain during the first hour of your test. But if you’ve thoroughly prepared for the quant and verbal sections of the test, and have watched some tape (such as our IR recordings or AWA labs) on what you need to do for the two warmup sections, you’ll do just fine early and can focus on playing your best once the quant section shows up on your screen.

2) Focus on One Question at a Time

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I have never met anyone who is better at algebra than he or she is at arithmetic. As good as a person may be with algebra, that person’s going to be even better with real numbers (arithmetic). How can we use that to our advantage on the test?

Algebra and arithmetic are very similar, but algebra uses variables where arithmetic would use real numbers. On certain GMAT problems, we can taken a problem in which we were given variables and use real numbers instead “ we’re turning algebra into arithmetic!

Note: a lot of my students will complain that this method takes too much time. Of course it does when you first start studying it. You’ve been doing algebra for years, but most of you are just learning how to turn algebra into arithmetic. Think how slow you were when you first started learning algebra. Put in the practice and you’ll pick up the speed!

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I’ve spoken with several students recently who are struggling with translating wordy quant problems into the actual math necessary to set up and solve the problem. Some people make too many mistakes when doing this, and others find that, though generally accurate, they take more time than they can afford. In the next two articles (this is part 1!), we’re going to talk about how to translate efficiently and effectively.

We’re going to do this by example: I’ll provide short excerpts from OG or GMATPrep problems, and then we’ll discuss how to know what to do, how to do the actual translation, and how to do so efficiently. Note that I’m not going to provide the full text of problems “ and, therefore, we’re not going to solve fully. That’s not our goal today.
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