Archives For Stacey Koprince

gmat-quant-help-tips-problemHow did it go last time with the rate problem? I’ve got another story problem for you, but this time we’re going to cover a different math area.

Just a reminder: here’s a link to the first (and long ago) article in this series: making story problems real. When the test gives you a story problem, do what you would do in the real world if your boss asked you a similar question: a back-of-the-envelope calculation to get a “close enough” answer.

If you haven’t yet read the earlier articles, go do that first. Learn how to use this method, then come back here and test your new skills on the problem below.

This is a GMATPrep® problem from the free exams. Give yourself about 2 minutes. Go!

* “Jack and Mark both received hourly wage increases of 6 percent. After the wage increases, Jack’s hourly wage was how many dollars per hour more than Mark’s?

“(1) Before the wage increases, Jack’s hourly wage was $5.00 per hour more than Mark’s.

“(2) Before the wage increases, the ratio of Jack’s hourly wage to Mark’s hourly wage was 4 to 3.”

Data sufficiency! On the one hand, awesome: we don’t have to do all the math. On the other hand, be careful: DS can get quite tricky.

Okay, you and your (colleague, friend, sister…pick a real person!) work together and you both just got hourly wage increases of 6%. (You’re Jack and your friend is Mark.) Now, the two of you are trying to figure out how much more you make.

Hmm. If you both made the same amount before, then a 6% increase would keep you both at the same level, so you’d make $0 more. If you made $100 an hour before, then you’d make $106 now, and if your colleague (I’m going to use my co-worker Whit) made $90 an hour before, then she’d be making…er, that calculation is annoying.

Actually, 6% is pretty annoying to calculate in general. Is there any way around that?

There are two broad ways; see whether you can figure either one out before you keep reading.

First, you could make sure to choose “easy” numbers. For example, if you choose $100 for your wage and half of that, $50 an hour, for Whit’s wage, the calculations become fairly easy. After you calculate the increase for you based on the easier number of $100, you know that her increase is half of yours.

Oh, wait…read statement (1). That approach isn’t going to work, since this choice limits what you can choose, and that’s going to make calculating 6% annoying.

Second, you may be able to substitute in a different percentage. Depending on the details of the problem, the specific percentage may not matter, as long as both hourly wages are increased by the same percentage.

Does that apply in this case? First, the problem asks for a relative amount: the difference in the two wages. It’s not always necessary to know the exact numbers in order to figure out a difference.

Second, the two statements continue down this path: they give relative values but not absolute values. (Yes, $5 is a real value, but it represents the difference in wages, not the actual level of wages.) As a result, you can use any percentage you want. How about 50%? That’s much easier to calculate.

Okay, back to the problem. The wages increase by 50%. They want to know the difference between your rate and Whit’s rate: Y – W = ?

“(1) Before the wage increases, Jack’s hourly wage was $5.00 per hour more than Mark’s.”

Okay, test some real numbers.

Case #1: If your wage was $10, then your new wage would be $10 + $5 = $15. In this case, Whit’s original wage had to have been $10 – $5 = $5 and so her new wage would be $5 + $2.50 = $7.50. The difference between the two new wages is $7.50.

Case #2: If your wage was $25, then your new wage would be $25 + $12.50 = $37.50. Whit’s original wage had to have been $25 – $5 = $20, so her new wage would be $20 + $10 = $30. The difference between the two new wages is…$7.50!

Wait, seriously? I was expecting the answer to be different. How can they be the same?

At this point, you have two choices: you can try one more set of numbers to see what you get or you can try to figure out whether there really is some rule that would make the difference always $7.50 no matter what.

If you try a third case, you will discover that the difference is once again $7.50. It turns out that this statement is sufficient to answer the question. Can you articulate why it must always work?

The question asks for the difference between their new hourly wages. The statement gives you the difference between their old hourly wages. If you increase the two wages by the same percentage, then you are also increasing the difference between the two wages by that exact same percentage. Since the original difference was $5, the new difference is going to be 50% greater: $5 + $2.50 = $7.50.

(Note: this would work exactly the same way if you used the original 6% given in the problem. It would just be a little more annoying to do the math, that’s all.)

Okay, statement (1) is sufficient. Cross off answers BCE and check out statement (2):

“(2) Before the wage increases, the ratio of Jack’s hourly wage to Mark’s hourly wage was 4 to 3.”

Hmm. A ratio. Maybe this one will work, too, since it also gives us something about the difference? Test a couple of cases to see. (You can still use 50% here instead of 6% in order to make the math easier.)

Case #1: If your initial wage was $4, then your new wage would be $4 + $2 = $6. Whit’s initial wage would have been $3, so her new wage would be $3 + $1.5 = $4.50. The difference between the new wages is $1.5.

Case #2: If your initial wage was $8, then your new wage would be $8 + $4 = $12. Whit’s initial wage would have been $6, so her new wage would be $6 + $3 = $9. The difference is now $3!

Statement (2) is not sufficient. The correct answer is (A).

Now, look back over the work for both statements. Are there any takeaways that could get you there faster, without having to test so many cases?

In general, if you have this set-up:

- The starting numbers both increase or decrease by the same percentage, AND

- you know the numerical difference between those two starting numbers

? Then you know that the difference will change by that same percentage. If the numbers go up by 5% each, then the difference also goes up by 5%. If you’re only asked for the difference, that number can be calculated.

If, on the other hand, the starting difference can change, then the new difference will also change. Notice that in the cases for the second statement, the difference between the old wages went from $1 in the first case to $2 in the second. If that difference is not one consistent number, then the new difference also won’t be one consistent number.

Key Takeaways: Make Stories Real

(1) Put yourself in the problem. Plug in some real numbers and test it out. Data Sufficiency problems that don’t offer real numbers for some key part of the problem are great candidates for this technique.

(2) In the problem above, the key to knowing you could test cases was the fact that they kept talking about the hourly wages but they never provided real numbers for those hourly wages. The only real number they provided represented a relative difference between the two numbers; that relative difference, however, didn’t establish what the actual wages were.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

gmat-quant-help-tips-problemIn the past, we’ve talked about making story problems real. In other words, when the test gives you a story problem, don’t start making tables and writing equations and figuring out the algebraic solution. Rather, do what you would do in the real world if someone asked you this question: a back-of-the-envelope calculation (involving some math, sure, but not multiple equations with variables).

If you haven’t yet read the article linked in the last paragraph, go do that first. Learn how to use this method, then come back here and test your new skills on the problem below.

This is a GMATPrep® problem from the free exams. Give yourself about 2 minutes. Go!

* “Machines X and Y work at their respective constant rates. How many more hours does it take machine Y, working alone, to fill a production order of a certain size than it takes machine X, working alone?

“(1) Machines X and Y, working together, fill a production order of this size in two-thirds the time that machine X, working alone, does.

“(2) Machine Y, working alone, fills a production order of this size in twice the time that machine X, working alone, does.”

You work in a factory. Your boss just came up to you and asked you this question. What do you do?

In the real world, you’d never whip out a piece of paper and start writing equations. Instead, you’d do something like this:

I need to figure out the difference between how long it takes X alone and how long it takes Y alone.

Okay, statement (1) gives me some info. Hmm, so if machine X takes 1 hour to do the job by itself, then the two machines together would take two-thirds…let’s see, that’s 40 minutes…

Wait, that number is annoying. Let’s say machine X takes 3 hours to do the job alone, so the two machines take 2 hours to do it together.

What next? Oh, right, how long does Y take? If they can do it together in 2 hours, and X takes 3 hours to do the job by itself, then X is doing 2/3 of the job in just 2 hours. So Y has to do the other 1/3 of the job in 2 hours. Continue Reading…

GMAT-sentence-correctionWelcome to the third part of our series focusing on the First Glance in Sentence Correction. If you haven’t read the previous installments yet, you can start with how to find a starting point on a Sentence Correction problem when the starting point doesn’t leap out at you.

Try out the First Glance on the below problem and see what happens! This is a GMATPrep® problem from the free exams.

* “Most of the purported health benefits of tea comes from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C that inhibit the formation of plaque along the body’s blood vessels.

“(A) comes from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C that

“(B) comes from antioxidants—compounds that are also found in beta carotene, vitamin E, and vitamin C, and they

“(C) come from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C, and

“(D) come from antioxidants—compounds that are also found in beta carotene, vitamin E, and vitamin C and that

“(E) come from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C, and they”

The First Glance definitely helps on this one: comes vs. come is a singular vs. plural verb split, indicating a subject-verb agreement issue. Now, when you read the original sentence, you know to find the subject.

So what is the subject of the sentence? It’s not the singular tea, though it’s tempting to think so. The subject is actually the word most, which is a SANAM pronoun.

The SANAM pronouns: Some, Any, None, All, More / Most

These pronouns can be singular or plural, depending on the context of the sentence. Consider these examples:

Continue Reading…

GMAT-sentence-correctionLast time, we talked about how to find a starting point on a Sentence Correction problem when the starting point doesn’t leap out at you. If you haven’t read that article yet, go ahead and do so.

The first step of the SC process is a First Glance, something that didn’t help out a whole lot on last week’s problem. Let’s try out the First Glance again and see what happens!

This GMATPrep® problem is from the free exams.

* “Often incorrectly referred to as a tidal wave, a tsunami, a seismic sea wave that can reach up to 150 miles per hour in speed and 200 feet high, is caused by underwater earthquakes or volcanic eruptions.

“(A) up to 150 miles per hour in speed and 200 feet high, is

“(B) up to 150 miles per hour in speed and heights of up to 200 feet, is

“(C) speeds of up to 150 miles per hour and 200 feet high, are

“(D) speeds of up to 150 miles per hour and heights of up to 200 feet, is

“(E) speeds of up to 150 miles per hour and as high as 200 feet, are”

What did you do for the First Glance? The glance is designed to give you an upfront hint about one issue that the sentence might be testing before you actually start reading the full sentence. Take a look at the beginning of the underline, including the beginning of all five answer choices.

The split is between up to and speeds of up to. There isn’t an obvious grammar rule here, so the issue is likely to revolve around meaning: do we need to say speeds of or is it enough to say just up to?

Think about this while reading the original sentence. What do you think?

The phrase reach up to could go in several different directions—is it going to say up to 150 miles in length? up to 150 feet high?—so it’s preferable to clarify right up front that the wave is reaching speeds of up to 150 miles per hour.

In addition, the sentence contains parallelism:

can reach up to X [150 miles per hour in speed] and Y [200 feet high]

The portion before the parallelism starts must apply to both the X and Y portions, so the original sentence says:

can reach up to 200 feet high

That might sound kind of clunky and it is: up to and high are redundant.

Okay, answer (A) is incorrect and answer (B) repeats both issues (it neglects to specify speeds of up to 150 and it contains faulty parallelism.).

Check the parallelism in the other choices:

“(C) speeds of up to [150 miles per hour] and [200 feet high]

“(D) [speeds of up to 150 miles per hour] and [heights of up to 200 feet]

“(E) speeds of [up to 150 miles per hour] and [as high as 200 feet]”

In answer (C), the Y portion is the measurement (200 feet), so the X portion should also be the measurement…but it’s nonsensical to say speeds of up to 200 feet high. Likewise, in (E), the Y portion is a prepositional phrase, so it matches the prepositional phrase in the X portion. Now, the sentence says speeds of as high as 200 feet—equally nonsensical.

The only one that makes sense is answer (D): speeds of up to 150 and heights of up to 200.

The correct answer is (D).

You might also have noticed, in the original sentence, that the last underlined word is the verb is. Sentence Correction problems always have at least one difference at the beginning of the underline and at the end, so glance down the end of the choices.

Interesting! Is vs. are. What subject goes with this verb? Here’s the original sentence again:

Often incorrectly referred to as a tidal wave, a tsunami, a seismic sea wave that can reach up to 150 miles per hour in speed and 200 feet high, is caused by underwater earthquakes or volcanic eruptions.”

The modifiers have been crossed out. The subject is tsunami, a singular noun, so the verb should be the singular is. Answers (C) and (E) are incorrect for this reason.

Key Takeaways: The First Glance in Sentence Correction

(1) Before reading the original sentence, make it a habit to glance at the word or couple of words at the start of the underline and each answer choice. Sometimes, the split will be obvious: an is vs. are split, for example, clearly indicates subject-verb agreement.

(2) Sometimes the split will be less obvious, as with up to vs. speeds of up to. In this case, if the split is fairly easy to remember, just keep the variations in mind as you read the original sentence, so that you can analyze the difference right away. You may see immediately that speeds of up to is more clear, and your knowledge that the sentence is testing this meaning might also alert you to some of the meaning issues introduced by the faulty parallelism.

(3) Making a subject-verb match in the midst of a bunch of modifiers can be tricky. Learn how to strip the modifiers out and take the sentence down to its basic core structure.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

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good-gmat-scoreA 780 is a great score, sure—but you don’t need that kind of score. You probably do need something higher than 500, though. How good is good enough?

The short answer to the question is this: a good score is a score that will make you competitive at a particular school. So the first question to ask yourself is where do you want to go?

Then, hit the Inter-web and find out what kinds of scores those schools report. Most schools report both an average score and a “middle 80% score” (the latter gives the score range for the middle 80% of people admitted in that year).

So, if Stanford has an average of 732 (which is what their website says as I write this!), then clearly you need a 750, right?

Wrong. Really wrong, in fact. I was inspired to write this article because of two recent blog posts written by my colleague Jeremy Shinewald, founder of MBA Mission. The posts are fantastic—and they are both linked in this article. They are mandatory reading for all of my students (and not because he mentions me in one of them!).

First, remind me what the word “average” means.

Right…in other words, many of the admitted students scored below 730. In fact, Stanford’s reported scoring range is from 550 to 790. (Yes, someone got into Stanford with a 550! I’m sure that person was absolutely amazing in some other way or ways, and so the admissions committee didn’t care about that one below-average data point.)

I’m not suggesting, of course, that you only need a 550 or 600 to get into Stanford. Ideally, you want to be pretty close to the school’s average. The school is not, however, going to ding you for getting “only” a 700. (You might get dinged for other reasons of course…)

But don’t take my word for it; read what Jeremy has to say on the topic.

What’s a good quant score? What’s a good verbal score?

Schools do check the Quant and Verbal sub-scores as well as the overall score—and this is another source of anxiety for test-takers. Have you heard about the 80/80? Many years ago (actually, we could be speaking in decades at this point), some people did talk about wanting to see 80th percentile sub-scores for quant and verbal. I haven’t been able to verify whether actual business schools ever said they wanted this, but the topic has been around for a long time.

As of early July 2014, there are now only two Quant scores above the 80th percentile: 50 and 51. Clearly, the top business schools don’t admit only people with 50s and 51s any more than they only admit people with 750 scores. There wouldn’t be enough people to go around!

So what’s going on? Percentiles are a relative ranking; they change over time. The sub-scores themselves are fixed. The skill level that it takes to score 45 today is the same skill level required to get a 45 five years ago, or fifteen!

In 2007, a Quant score of 45 was the 77th percentile; today, a 45 is the 63rd percentile. But the underlying skill needed to reach that score hasn’t changed one bit, and here’s the important part: the schools know this.

They aren’t actually interested in how your percentile ranking stacks up against the rest of the pool of test takers. Their main goal is to make sure that you can handle the rigorous work that will be required of you when you reach b-school. Pay attention to the actual scoring level, which tells you something real. A quant 45 was once “good enough” for schools and nothing has changed: it still is today!

Here’s Jeremy again on this topic.

But seriously…If I just get a 750, I’ll be a shoo-in, right?

Wrong. The schools don’t admit based on GMAT scores. The GMAT is more of a threshold indicator: show me that you can handle my rigorous program, and then I’ll consider the other (more important) parts of your application, such as your work history, your essays, your recommendations…in short, your story. That’s how I’ll actually make my decision about your application.

Seriously, consider who’s telling you that you don’t actually need these crazy high scores. I work for a test prep company; our whole reason for existing (and making money!) is to help people get higher scores. If even I’m telling you that you don’t need a 750 or a 50 or 51 on quant, then believe it! :)

But…But…This is the only thing I can control…

Here is the heart of the anxiety around this test. Your GPA is already set. Your work career can’t be substantially changed in a few months; your history is what it is. So you feel as though this is it: the GMAT is how you can give yourself the best possible chance to get in!

You can’t bomb the test, of course, but there are a lot of other things you can be doing with your very valuable time than chasing a 750 (or even a 720). You could actually pick up an extra project at work, try to get yourself into a team leader or mentor role, or work towards a promotion.

Also, don’t underestimate the time and effort required to put together a great application package. Ideally, your package will tell a coherent story, something that fits together across all pieces of the application and jumps off the page so that the admissions committee can really visualize you and get a sense of who you are and why they want to have you at their school. For instance, have you thought about what you want to tell your recommenders to emphasize (in terms of both strengths and weaknesses) so that their recommendations dovetail with your own essays?

I’m not going to give a bunch of application advice because that’s not my area of expertise—but you can control a lot more of your application than the GMAT score. Go read more on Jeremy’s blog to find out how.

(And, all right, fine: if you want to get better at the GMAT, start here!)

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GMAT-sentence-correctionOn some Sentence Correction (SC) problems, an error jumps out at you immediately. On others, you’re left trying to figure out where to start. How do you dig in when the starting point isn’t obvious?

Try this GMATPrep® problem from the free exams and then we’ll talk about it.

* “A recording system was so secretly installed and operated in the Kennedy Oval Office that even Theodore C. Sorensen, the White House counsel, did not know it existed.

“(A) A recording system was so secretly installed and operated in the Kennedy Oval Office that

“(B) So secret was a recording system installation and operation in the Kennedy Oval Office

“(C) It was so secret that a recording system was installed and operated in the Kennedy Oval Office

“(D) A recording system that was so secretly installed and operated in the Kennedy Oval Office

“(E) Installed and operated so secretly in the Kennedy Oval Office was a recording system that”

The first step on SC is to glance at the start of the underline (even before you read the sentence) in order to see whether the opening change in the answers gives you a clue about where to start. In this case, the underline starts right at the beginning of the sentence. A scan down the beginning of each answer choice signals exactly nothing on this problem. Now what?

Okay, on to step 2: read the original sentence (for both meaning and grammar). What do you think?

The sentence sounds kind of clunky. It uses an idiom (so X that Y). Is the idiom used correctly? Here are some correct examples.

She was SO extraordinarily lucky THAT she actually won the lottery three separate times.

The CEO was SO preoccupied with profits THAT he missed the signs of a market collapse.

Notice the structure in these examples. There are actually two subject-and-verb pairs—one set before the word that and one set after. In addition, the Y portion of the sentence (after that) represents evidence to support the scenario in X or some consequence of that scenario. The fact that she won the lottery three times is evidence that she’s really lucky. The CEO’s preoccupation actually caused the CEO to miss signs of the collapse.

The original sentence has this same structure:

(A) The system was SO secretly installed THAT even Sorensen did not know it existed.

This structure, then, is correct in the original sentence. What about the other answers?

Here’s where things start to get messy! Strip down the structures for each choice:

(B) SO secret was the system (even Sorensen did not know it existed.)

(C) It was SO secret THAT a system was installed (even Sorensen did not know it existed.)

(D) A system that was SO secretly installed (even Sorensen did not know it existed.)

(E) Installed SO secretly was a system THAT (even Sorensen did not know it existed.)

Answer (B) is missing the that portion of the idiom. People often skip this word in real life but notice what happens when you do so:

She was so late, I wasn’t even sure she was coming!

There are two complete sentences connected only by a comma. That’s a comma splice error! Eliminate (B).

Answer (D) does have the word that, but it’s before the so. This sentence turns out to have no main verb for the subject (system). That was so secretly installed modifies system, and even Sorensen… doesn’t provide a verb for system. Eliminate (D).

In both cases, the missing that signaled a problem with sentence structure.

Answer (C) has the that…but wait a second. It moved. Is it still okay?

No! That a system was installed is just a modifier of secret; it’s not actually finishing off the idiom by providing some follow-on info or consequence of the so portion. There should still be a that before even Sorensen:

It was SO secret that a system was installed THAT even Sorensen did not know it existed.

(That sentence may still sound clunky to you. The double that may be tripping your “sounds bad!” instincts, or possibly the passive It was opening. I definitely wouldn’t write the sentence this way myself!)

Eliminate (C). Okay, what about answer (E)?

The so X portion of the sentence should provide the opening information that is later addressed in the that Y portion. What was so surprising that Sorensen didn’t know?

The surprise was that this system had been installed and was being operated in the area where he worked. In answer (E), though, those verbs come before the so—that is, they are not part of the X portion of the sentence. Eliminate (E).

Only answer (A) uses the idiom to convey the proper meaning: This system was SO secretly installed and operated THAT even someone who worked there didn’t know about it!

The correct answer is (A).

Key Takeaways: Meaning, Structure, and Idioms in SC

(1) When you don’t spot an obvious way into the sentence, consider examining the core sentence, particularly if the sentence contains a structure that extends across nearly the whole thing, such as parallelism or an idiom (as in this case).

(2) Messing up an idiom can lead to both meaning and structure errors. Even if you don’t know the idiom, then, you might still be able to narrow down the answers! In the problem above, answer (B) was a run-on and answer (D) was a fragment, all because the usage of the idiom was messed up.

(3) Stripping the sentence down to the minimum necessary to test the sentence (and idiom) structure takes some time but may be your best shot at answering the question. This may not get you all the way to the right answer, but there’s a good chance it will help you eliminate some wrong answers.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

Read the next part of this series: GMAT Sentence Correction: Where do I start? (Part 2).

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gmat-study-tipsHave you ever worked with someone who inevitably managed to come up with things to do that were a complete waste of time? Maybe it was an insecure boss who was never confident about what he was doing, so he went for the “everything and the kitchen sink” approach to generating deliverables in the last few days before the deadline. Or maybe it was a fellow student on a group project, someone so diligent (cough, cough) that she wanted to turn in a 20-page report when the teacher suggested 10 pages (and actually specified a 12-page limit).

You know who I’m talking about, right? We’ve all run across these situations in our academic or working lives. You want to be polite…but you also want to get your work done and not waste time on activities that don’t really help you reach the overall goal.

The GMAT is trying to waste your time

Okay, the test writers are not literally sitting there cackling and saying, “How can we get them to waste their lives?!?” But the overall sentiment still holds because of the way that the GMAT is constructed. You already know the classic “If you get something right, they give you something harder” pattern, right?

Well, at some point, that “something harder” is going to be something that isn’t worth your time. You’re probably not going to get it right no matter what you do. Even if you do, you’re going to use up valuable time that you could be using on other problems.

Most important of all, you’re going to be using up your finite brain energy on something that probably isn’t going to pay off. How many times in your life have you crashed towards the end of a test or a long day at work because your brain just couldn’t keep going any longer? The GMAT is a “where you end is what you get” test: if you crash before the end of the section, your score will suffer greatly.

This is basically no different than that co-worker who’s trying to get you to build a marketing presentation when the client has specifically requested that you analyze the pros and cons of acquiring a competitor. Tomorrow at the client meeting, it won’t matter how good your intentions were. Your client is going to be mad that you wasted time on something that doesn’t actually help them.

Continue Reading…

OG2015GMAC just released new 2015 editions of its three The Official Guide for GMAT® Review books. Here’s what you need to know as you decide whether to buy these books and how to use them.

What changed?

The three books in question are The Official Guide for GMAT Review 2015 (formerly known as the 13th edition of the Official Guide, or OG), The Official Guide for GMAT Quantitative Review 2015 (formerly known as the 2nd edition of the Quant Review), and The Official Guide for GMAT Verbal Review 2015 (formerly known as the 2nd edition of the Verbal Review). I’ll refer to these throughout this article as OG2015, QR2015, and VR2015, respectively.

The questions (and explanations) contained in all three 2015 versions are the same as the questions (and explanations) in the previous versions. There are no new questions.

The new editions do come with special codes to access an online software program that contains the problems from the books. Now, when you want to do a set of random OG problems, you don’t have to create the sets for yourself—you can have the online software do it for you. (OG2015 also still provides online access to the 50 Integrated Reasoning questions that come with the 13th edition of the book.)

The online software also has some short videos (one for each book) starring the incomparable Dr. Lawrence Rudner, Chief Psychometrician for GMAC, answering frequently asked questions from students.

How does the software work?

The software for all three books gives you the ability to choose Practice mode or Exam mode. In addition, OG2015 offers a Diagnostic test mode that contains the questions from chapter 3 of the printed book.

Certain features are offered in all three modes:

- Question Type, Number, and Difficulty. You can choose from among the different question types (PS, DS, SC, CR, RC), as well as by difficulty bucket (easy, medium, hard, or all). You can also decide how many questions you want to be in the set.

- Timing. The software will keep track of how much time you spend per question, as well as your overall time for that set of questions. (It does not, though, give you a time limit, so you will have to set one for yourself.)

- Bookmarks. You can bookmark problems that you want to remember for some reason—maybe your guesses or the ones that you want to try again before checking the answer or explanation.

- Calculator. Yes, the software offers a calculator, even though you’re not allowed to use a calculator on the quant section of the real test. My recommendation: pretend this button doesn’t exist.

- Pause. You can pause the question set. This is useful if someone suddenly rings your doorbell, but do not pause the software while continuing to work on the problem. Otherwise, your data will be skewed and you won’t really be able to tell what your strengths and weaknesses are.

In the Diagnostic and Exam modes, you can only move forward in the question set (as on the real exam), but in Practice mode, you can move back and forth. If you come back to a problem for the second time, the software will actually remember how much time you spent before and will start counting your time where you left off! I was really impressed with this feature.

I do have to warn you about three other somewhat-faulty features (maybe these will be changed in future). First, when you click to go to the next question, the software does not ask you to confirm. That’s fine in Practice mode, where you’re allowed to go backwards, but in Diagnostic and Exam modes, if you accidentally click “next question,” you will be moved to the next problem even if you have not yet entered an answer—and there is no way to go back.

Second, in any of the three modes, you’ll be able to go to a results screen when done with a question set. For both Exam and Practice modes, these question sets will be saved and you’ll be able to review them at any time in the future. In Diagnostic mode, however, you can only see the results screen right after you have finished the problem set. Once you close out of that area (or out of the software entirely), that data will disappear, so make sure you take screen shots of the results screen before you leave that area of the program. (In fact, I recommend taking the screen shots immediately after finishing a Diagnostic set. I accidentally clicked something that took me out of that part of the program and lost all of my data before I could review it.)

Third, in both Practice and Exam modes, the RC questions are offered one at a time, not in sets of 3 or 4 (as on the real test). For this reason, I recommend doing RC questions out of the physical book. Reading an entire passage only to answer a single question is not a good use of study time.

I was also excited to see that the Practice mode offered a “notes” feature, where you can actually type notes to yourself while working on the problem. I was disappointed that those notes seemed to disappear afterwards. When I was reviewing the results screen and the problem explanations, I couldn’t find any way to access my notes again.

How do I get the most out of these new books?

If you already have the previous incarnations of these books (OG13, VR2, and QR2), then I don’t actually recommend buying the new editions unless money is not a concern for you. The most important thing is to have access to the questions themselves. While the new software does make it much easier to set up problem sets, many people probably aren’t going to pay $46 just for that.

If you don’t yet have these books, though, then of course you’ll want to get the 2015 editions. In that case, here’s how I would use the new features:

1. In the first week or two of your study, take the Diagnostic mode tests. I would do these in 5 separate sittings, one for each question type. You don’t need to set yourself a hard overall time limit, but do pay attention to that clock and be honest with yourself when a problem just isn’t happening. Guess and move on. (Note: if you’re taking our class, then you can dispense with this step and save the problems for review later in your studies.)

2. As you work through whatever material you’re using to learn all about the math, grammar, and question types tested on the GMAT, you will initially try just a couple of OG problems that directly test whatever you recently studied. In this case, you won’t be using the OG software because the software doesn’t let you select by topic.

After you get at least halfway through your study material though (e.g., about 3 of our 5 quant books, or halfway through the chapters in the SC book), you can start to set up random sets of questions for yourself using the software’s Practice mode. When you’re offered a question on a topic you haven’t studied yet, just do your best; this will help you to have an idea of your strengths and weaknesses so that you know how much time to spend when you do get to that topic.

Whether you want to do random sets of problems or choose specific topics, here are some guidelines for creating your own OG problem sets.

3. Save Exam mode for a bit later in your studies, after you’ve been through all of your main study material once. Both Practice and Exam modes are pulling from the same pool of questions, but Exam mode imposes some additional restrictions that make your practice closer to the real test (for example, you can’t go back to questions that you’ve already completed).

In sum

Everyone should be studying with the Official Guide materials—nothing is better than the real thing! If you already have the 13th edition or 2nd edition books, don’t feel that you must buy the 2015 editions, but if you don’t, then certainly get the latest versions and take advantage of the new online problem set program.

Happy studying!