Ben Franklin would kill the GMAT
February 8, 2013
Read this article. It’s about how Benjamin Franklin, a notable and influential founding father of the United States, structured his life so as to be as productive as possible and always live knowing tomorrow is, in fact, today. In the article, the author, Samuel Bacharach, a labor management professor at Cornell University, lists five habits Franklin employed to ensure procrastination was not part of his personal description.
In this post, I will apply each habit as listed by the author of the article in order to provide a framework for a productive GMAT study schedule—one that begins today and does not relent until Test Day!
1. Start a group and share knowledge. GMAT study is too often a very lonely endeavor. Despite my encouragement, it is with rare frequency my students organize study groups. I could speculate reasons as to why—busy schedules, different strengths/weaknesses, not wanting to exhibit weakness in front of others, lack of an idea about how to actually structure group study—and all are totally understandable. However, I really wish this were not the case. I have had groups jump at the chance to meet with their peers and have received a lot of positive feedback about the benefits.
Surrounding yourself with others plodding along a similar road to yours helps stimulate ideas, expand understanding, derive opportunities to learn by teaching, and motivate you to show up and get to work. Create a GMAT Junto!
2. Attack opportunities. You will never recognize opportunities if you do not look for them. A constructive attitude about what constitutes an opportunity during GMAT prep is a wondrous and invaluable thing. Really, several items on this list are opportunities all GMAT test preppers can expect to find. Starting a study group, making mistakes, and planning are all opportunities to get the most out of your study time.
As we discuss each, view them through the lens of opportunity and continue to approach GMAT prep in this way. For example, freaking out during a practice test gives you the chance to learn to recognize stress when it arises and devise a plan to overcome it. Test prep classes and the resources that accompany them are an opportunity to learn how to get the score you deserve to get. A previous misstep in calculating the tremendous challenge of the GMAT is an opportunity to make sure round two is the last round.
3. Time is a commodity in short supply. Time management, study schedules, and respect for the test are common themes in my writing on Kaplan’s GMAT Blog. For some thoughts on the matter, read these three posts: The GMAT Needs a Runway, How to Get Ready for the GMAT, and MBA Decision: The Financial Times Explores the Process.
4. Make a list. Beyond the pro-and-con list described in the article, plan out everything with regard to GMAT prep. So you can see for yourself, definitely take the time to list the good and bad aspects of a top notch study regimen, but continue to utilize lists during the prep cycle to maintain momentum and efficiency.
Something I tell all of my students to do is take the last 5-10 minutes of every study session to plan what they will do when they sit down for the next session. Doing this ensures you will hit the ground running and not be overwhelmed under the weight of all the stuff you could be doing. The latter situation usually results in a useless foray of social voyeurism on Facebook—something that definitively will NOT help improve your GMAT score.
5. Fail often; fail hard; but don’t expect to. Quite simply, celebrate mistakes. Each stumble on Preparation Road makes it that much more likely you will not make the same mistake on the only day it matters: Test Day. A mistake is an opportunity to learn.
Did you get it wrong because you got the right answer to the wrong question? Did you miss it because you searched outside the scope of the passage or argument? Did you run out of time because you gave two “tough nut” questions ten minutes of effort?
If I have said it once, I’ve said it a thousand times: tenacity is what builds high GMAT scores. After all, in the immortal words of Henry Ford:
”Whether you think you can or can’t, you’re right.”
Master Reading Comprehension Question Types: Part II
September 6, 2012
In a blog last last week, I talked about the importance of identifying the common question types in the reading comprehension portions of the GMAT and delved into the specifics for detail and global questions. Today, let’s continue that deeper look at the specifics for the common reading comprehension questions with a look at inference and function (logic) questions. Specifically let’s look at how to spot them, how to predict using the pattern behind the question, and how to spot the most common wrong answer types. Both of these questions generally constitute the harder or more commonly missed set of questions in the reading comprehension.
One of the most commonly missed reading comprehension questions is the inference question because of how it is treated on tests versus our common everyday use of inference. First of all, to spot them you are looking either for something that references “is true” or uses “infers,” “implies,” or “suggests” in the question stem. The most common phrasing is “most likely agree” in an inference stem. Once you see any of these triggers, immediately switch your mindset to look for what MUST be true. Because the language is soft in the question stem, test-takers usually just consider and look for what COULD be true. That will lead you straight to trap answer choices. You MUST look for what MUST be true. I even started mentally adding “must it be true that…” before reading each answer choice. Trust me; this will revolutionize your approach to inference questions. In addition to looking for what MUST be true, lean toward choices that have what I would call softer or squishy wording like “some,” “could,” “likely,” etc. It’s much easier to write a MUST be true answer about some things than it is to write a MUST be true about all things.
In addition to identifying the right answer, knowing the choices that you can eliminate can be just as helpful. The most common wrong answer types on inference questions are the out of scope and extreme choices. As stated above, it’s harder to write something that MUST be true about everything. Therefore, lean away from the extreme wording. Also, many out of scope choices COULD be true, so they are appealing. Asking whether it MUST be true will help you avoid these traps.
The last of the big four reading comprehension question types is the function (logic) question. These questions ask about WHY an author included some detail in the passage. You can spot these because they commonly include a line reference and include phrasing such as “functions to,” “in order to,” or “serves to.” In order to answer these questions efficiently and effectively, look to the opinion or main idea right around that detail; context is key in these questions. Typically that means that you are looking at the author opinion that is directly above or in the topic sentence of that particular paragraph. Occasionally, the point supported can come after the detail. Expanding out beyond the lines mentioned in the question is crucial to taking care of these questions adeptly. With function questions, the traps or most common wrong answers are those that pertain to the detail but don’t answer the question why – they distort what the question is asking. To avoid these make sure you always align yourself to look at the context.
Outside of these four primary question types (detail, global, inference, and function), there are a few outliers such as application, vocab-in-context, strengthener, and weakener questions. If a question doesn’t clearly fit one of the big four, don’t try to force the pattern. The patterns take time and repeated practice to get used to, but if you want to take your reading comprehension score to the next level on test day, aligning your approach with the specifics of each type is the way to go!
The GMAT and the Primacy of Doing
August 29, 2012
For a previous post, a colleague of mine offered up the embedded video at the top, which I love. He said, “That video clearly demonstrates the “primacy of doing.” Ever since receiving his email, the phrase “primacy of doing” has echoed in my mind on a seemingly endless loop.
I had already begun to kick around a post idea on Kaplan’s Official Test Day Experience—mainly because I think it is one of the most attractive and impactful GMAT prep opportunities our company offers. If you are a Kaplan student who is on the fence about signing up for the Official Test Day Experience, or, you are not yet a Kaplan student and wonder what this is, here’s the scoop:
All Kaplan GMAT students* have an exclusive opportunity to take a practice test on-site at an official Pearson/VUE testing center. In fact, you can take it at the very same testing center where you will sit for the actual GMAT exam.
Think how meaningful that is! To take a full-length computer adaptive practice GMAT in the very room where you’ll take the real thing and have the opportunity to review a detailed breakdown of that test in its entirety is… All of my students who exploit this aspect of their course rave about how happy they are to have done so and how much it will assuredly help them on test day. In class, I then use their experiences to inspire and convince their colleagues to do the same.
When reading through some articles on BusinessWeek.com, I came across an interesting thought on “authenticity.” The author had been searching for a definition of the word, and he eventually created his own: closeness to the source. As I am sure you’ve already done, connect this idea with those surrounding the Official Teat Day Experience and the phrase “the primacy of doing.” How could I not write this blog post??
To all Kaplan students reading this post who have taken a practice test at a testing center AND to all people who have taken the official GMAT: please reply in the comments section below with your thoughts on the value of knowing exactly what to expect from your test day environment.
The 4 Truths of the GMAT Argument Essay
August 25, 2012
As you likely know, with the inclusion of the Integrated Reasoning (IR) section came the exclusion of the one of the previously required essays. Before the test change, GMAT test takers built their Analytical Writing Assessment (AWA) score on the backs of two essays: Analysis of an Argument and Analysis of an Issue. These two essays would be scored independently—by one human and one computer—then those two scores would be averaged for a total AWA score on a 0-6 point scale in ½-point increments. In order to keep total testing time at 3.5 hours, test makers decided to cut the thirty-minute Analysis of an Issue essay and insert a thirty-minute Integrated Reasoning section.
So what can we make of this decision? Now, let’s not bicker about the Integrated Reasoning section here; it is what it is and we all have to deal with it. Rather, let’s focus on the essay left standing. Since we still have to write, are we better off with the Argument essay over the Issue essay? And, if so, is there a way we can ensure a top-scoring essay on test day? Good news: yes and yes.
First, writing an Argument essay over an Issue essay is preferable because of all the work we do studying GMAT Critical Reasoning (CR) questions. Seventy percent of CR questions we will see on test day will come from what is known as the Assumption Family of question types (aka, the Argument Family). In each of these question types—Assumption, Strengthen, Weaken, and Flaw—we always approach in the exact same way. That is, we identify the Conclusion, then we identify the Evidence, and then we can tease out the author’s primary Assumption(s) by applying our highly tuned critical thinking skills. You see, a GMAT argument will always state both a conclusion and evidence for the conclusion. What we will never be given, what the author will never state explicitly, are the underlying assumptions that allow this evidence to lead to this conclusion. But, in order to answer Assumption Family questions we must identify what those unstated assumptions are.
The good news about the Argument essay can be summed up by “The Four Truths” present in every single essay prompt created:
- There will be a Conclusion.
- There will be Evidence.
- There will be Assumptions linking the Conclusion and Evidence.
- Those Assumptions will be flawed.
Beautiful, right? The better we get at Critical Reasoning, the easier deconstructing the AWA essay prompt will be. In the Issue essay, we had to come up with our own ideas, reasoning, and support for taking a particular position on an issue provided. However, in the Argument essay, all we need is tucked away within the prompt itself. Sure, we have to do some detective work to sniff it out, but it is comforting to know it’s there and that we definitely have developed the skill to find it.
OK, so what about the other question: Is there a sure-fire way to churn out a top-scoring essay no matter what the given argument is? You bet. Quite simply, you’ll open by restating the conclusion and evidence in your own words. Then, you’ll identify at least two flawed assumptions and explain why they are flawed—one assumption per paragraph. After that, you’ll talk about how the argument could be strengthened (here, you can just feed off of what you said was wrong with it), then you’ll wrap up with a conclusion. That’s it.
As I mentioned at the beginning of this post, your GMAT essay is going to be scored by one human and one computer. I suggest reading my previous post titled “GMAT essays: Computers score your work, and they are really good at it” to learn more about those computers. But just in case you’re running short on time, I’ll give you the gist…
When that human grader gets to your essay—you know, the one you toiled over for half an hour—what do you think that human had been doing right before your essay popped up on their screen? Grading essays. And what do you think that human is going to do after they finish with your essay? Grading essays. And how much time do you think they will devote to evaluating your little essay baby that you worked so hard to compose? Under two minutes, even as little as one. So, then, what is that human trying to do? Emulate a machine.
The aforementioned structure of an Analysis of an Argument might seem bland and formulaic, but you need to appreciate that you are writing for a machine and someone trying their darndest to act like one. Feed the machine and you will be rewarded.
Do you have more questions about the argument essay or the test change? Post them in the comments and we’ll tackle them one at a time.
Tough GMAT Probability Questions
August 16, 2012
Tackling some of the tougher GMAT probability questions efficiently relies on both steady practice and your ability to make two key decisions well. First, you will need to quickly and accurately assess the total number of possible outcomes (the denominator of your probability equation). Second, within a multitude of possible approaches, you will need to determine the most efficient route to calculate the number of desired outcomes (the numerator of your probability equation).
With the clock ticking away on your GMAT CAT, figuring out the total number of possibilities can be time-consuming and fraught with room for error. For instance, if a question asks about the probability of getting at least 2 heads on 5 coin tosses, you could sit there all day writing out possibilities:
HHTTT
HTHTT
HTTHT
So forth and so on. I know I got dizzy with the possibilities just writing those three out. There is a better and more efficient way. For every coin that you toss there are 2 possibilities. You can think of the total possibilities like a permutation problem.
__2__ __2__ __2__ __2__ __2_
1st 2nd 3rd 4th 5th
Just like in a GMAT permutations question when we are trying to determine the total number of codes possible or 4-digit numbers, we would multiply these individual probabilities together. Therefore, there are 2x2x2x2x2 = 2^5 = 32 total possibilities.
Next, we need to look at the numerator (desired outcomes). We want to find the all of the possibilities that have at least 2 heads, which means that we could have 2 heads, 3 heads, 4 heads, or 5 heads. To do so, we would need to count all of the different ways that these possibilities could be arranged. Again, we find ourselves in a situation that will be time-consuming and fraught with error. Instead of going down this path, remember that the sum of the probabilities of a complete set of mutually exclusive possible outcomes is 1. Thus, as is often the case on “at least” probability questions, we can look for those options that are restricted. Then we only have to count the options that have 1 or 0 heads.
TTTTT
HTTTT
THTTT
TTHTT
TTTHT
TTTTH
There are only 6 of those, instead of the 26 possibilities the other way.
Finally, we can either subtract 6/32 from 1 in order to remove all of the restricted possibilities from 1 or we can subtract 6 from 32 and use the result as the desired possibilities. Either way, the answer is 26/32, which you can reduce down to 13/16.
Let’s look at another to make sure we have this down.
Question
A test has 5 multiple-choice questions. Each question has 4 answer options (A,B,C,D). What is the probability that a student will choose “B” for at least four questions if she leaves no questions blank? Pause a moment and try it for yourself first.
Step 1: Total number of possibilities
There are 5 questions and each has 4 possibilities, so our total possibilities would be 4x4x4x4x4 = 4^5 = 1024
Step 2: Approach Desired Strategically
Here there are far more possibilities for 0, 1, 2, or 3 “B’s,” so let’s get a total for 4 or 5 “B’s”.
All B’s — B,B,B,B,B
Four B’s — A,B,B,B,B – B,A,B,B,B – B,B,A,B,B – B,B,B,A,B — B,B,B,B,A
C,B,B,B,B – B,C,B,B,B – B,B,C,B,B – B,B,B,C,B – B,B,B,B,C
D,B,B,B,B – B,D,B,B,B – B,B,D,B,B – B,B,B,D,B – B,B,B,B,D
3 x 5 = 15 because we can repeat the same pattern for each letter other than B
We can also calculate the total possibilities of 4 B’s by calculating the possibilities for each “no-B” position.
No-B,B, B, B, B = 3x1x1x1x1 = 3
B, No-B, B, B, B = 1x3x1x1x1 = 3
B, B, No-B, B, B = 1x1x3x1x1 = 3
B, B, B, No-B, B = 1x1x1x3x1 = 3
B, B, B, B, No-B = 1x1x1x1x3 =3
A total of 15 possibilities with 4 B’s in the mix
That gives a total of 16 different ways that a student can choose at least 4 B’s here.
16/1024 = 1/64 as our final probability.
Keep these two decisions in mind each time that you approach a tough probability question on the GMAT quantitive section. You don’t have to write out all of the possible outcomes in order to tackle these on test day!
The language of probability can take a while to learn, especially if you are unfamiliar or out of practice with it to start. Post your questions below, and we can help you get on track.
GMAT Quantitative Section: Probability Translation
August 8, 2012
Translating word problems into algebra is a staple skill of GMAT test-takers, one that underlies countless problems in practice and on Test Day. But some challenging translations occur as part of probability and combinatorics problems. That’s because a pair of the most basic words in the English language, “And” and “Or,” suddenly become overburdened with mathematical significance.
“And” is the simpler of the two. When “And” represents independent choices—cases in which one option or arrangement has no impact on the other choice—just multiply the outcomes. For instance:
“The number of ways to purchase three board games and two video games” is an independent choice. The board games we pick have no impact on the video games we pick. So, to translate: [The number of ways to purchase three board games] × [the number of ways to select two video games]. Of course, we’d need the combination formula to find actual values—but we’d know what to do with those values once we got them.
“Or” is a little more complicated. It’s confusing even in conversation, after all—if I say that you can have cake or ice cream for dessert, can you have both if you want? When you CAN have both, you can treat the problem similarly to an overlapping sets problem. But in most cases on the GMAT, the “Or”s will be mutually exclusive—for instance, if you want to know the odds of drawing a heart or a diamond out of a deck of cards, there is no card that is both a heart or diamond.
A mutually exclusive OR can be translated as a “plus.” That’s all you have to do. So:
“The probability of drawing a heart or a diamond from a deck of cards,” which is the odds of one of two mutually exclusive events occurring, translates to: [The probability of drawing a heart] + [The probability of drawing a diamond].
Today’s problem of the day hinges on those same ideas. Read carefully—you’re solving for the odds of one of two outcomes (an OR), but each of those two outcomes is the specific result of two independent events (an AND). Be systematic in your translation, and I’m sure you’ll get the right result.
Post your answers below before you read the solution, and we can go over them…
Question:
Each person in Room A is a student, and 1/6 of the students in Room A are
seniors. Each person in Room B is a student, and 5/7 of the students in Room
B are seniors. If 1 student is chosen at random from Room A and 1 student is
chosen at random from Room B, what is the probability that exactly 1 of the
students chosen is a senior?
(A) 5/42
(B) 37/84
(C) 9/14
(D) 16/21
(E) 37/42
Solution:
Step 1: Analyze the Question
This is a complex question, but it can be broken down into
simple steps. As with any probability question, we must first
consider all of the scenarios in which the desired outcome
can be true. In this question, there are two different ways
in which exactly one of two students chosen is a senior.
Either (i) a senior is chosen from Room A and a non-senior
is chosen from Room B or (ii) a non-senior is chosen from
Room A and a senior is chosen from Room B.
Step 2: State the Task
Determine the probabilities of the two scenarios above and
add them together.
Step 3: Approach Strategically
Let’s start with (i) and find the probability that a senior is
chosen from Room A and a nonsenior is chosen from Room B.
The probability that the student chosen from Room A is a
senior is 1/6 .
The probability that the student chosen from Room B is not
a senior is 1- 5/7=2/7
So the probability that the student chosen from Room A
is a senior and the student chosen from Room B is not a
senior is (1/6) x (2/7) = 2/42 .
Let’s not simplify this yet, because we can expect that the
probability we will find when working with (ii) will also
have a denominator of 42.
Now let’s work with (ii). Let’s find the probability that a
nonsenior is chosen from Room A and a senior is chosen
from Room B.
The probability that the student chosen from Room A is not
a senior is 1 – 1/6 = 5/6 .
The probability that the student chosen from Room B is a
senior is 5/7 .
So the probability that the student chosen from Room A
is a not a senior and the student chosen from Room B is a
senior is (5/6) x (5/7) = 25/42 .
Now we sum the total desired outcomes. The probability
that exactly one of the students chosen is a senior
is (2/42) + (25/42) = 27/42 = 9/14 .
(C) is correct.
GMAT Coordinate Geometry
August 1, 2012
The key to many GMAT coordinate geometry questions is to remember that coordinate geometry is just another way of expressing the possible solutions to a two variable equation. Each point on the line in a coordinate plane corresponds to a solution for the equation of that line.
The base equation for a line is y = mx + b, where b is the y intercept, or the point at which the line crosses the y-axis, and m is the slope, or the steepness of the line. More specifically, the slope of a line is the change in the y coordinates divided by the change in the x coordinates between any two points on the line.
While understanding the basic format for an equation of a line can be very useful on the GMAT quantitative section, you will encounter GMAT problems in which it is faster and easier to think of the problem in algebraic terms. In such cases you should think of the equation as an algorithm that will produce the y value given any x value. This is the reason that the x values are sometimes referred to as inputs and the y values as outputs.
For example, if your answer choices are solution sets and you are asked to determine which option is on the line given in the y = mx + b form, rather than graphing the line and trying to determine which point falls on it, which is especially difficult as you will not have graph paper, you can plug each x value into the equation and determine which one produces the appropriate y value.
On test day, the key is to remember that coordinate geometry is just a way of expressing algebraic concepts visually. Thus, we can often treat these problems as algebra rather than as geometry. To see this in action, try the problem below.
Question:
In the xy-coordinate system, if (m, n) and (m 1 2, n 1 k) are two points on the line
with the equation x 5 2y 1 5, then k 5
(A) 1/2
(B) 1
(C) 2
(D) 5/2
(E) 4
Solution:
Step 1: Analyze the Question
For any question involving the equation of a line, a good
place to start is the slope-intercept form of the line,
y = mx 1 b. Remember that if you have two points on a
line, you can derive the entire equation, and if you have an
equation of the line, you can calculate any points on that
line.
Step 2: State the Task
We are solving for k, which is the amount by which the
y-coordinate increases when the x-coordinate increases
by 2.
Step 3: Approach Strategically
The slope of a line is the ratio between the change in y and
the change in x. In other words, every time the x-coordinate
increases by 1, the y-coordinate increases by the amount
of the slope.
The equation of the line in the question stem is defined as
x = 2y + 5. We must isolate y to have slope-intercept form:
So the slope of this line is 1/2 . This means that for every
change of +1 in the x direction, there is a change of + 1/2
in the y direction. Then we know that, because there is an
increase in 2 units in the x direction when moving from
m to m + 2, there must be a change of 1 unit in the y
direction when moving from n to n + k. So k = 1.
Since there are variables that eventually cancel (m and n
are not part of the answers), we can Pick Numbers. Let’s
say that you choose the y-coordinate of the point (m, n) to
be 0 to allow for easier calculations. Using the equation
we’re given to relate x- and y-coordinates, we can calculate
the x-coordinate:
So (m, n) is the point (5, 0).
Now we’ll plug our values of m and n into the next point:
(m + 2, n + k). That yields (7, k). All we have to do is plug
an x-coordinate of 7 into the equation to solve for k, the
y-coordinate:
Answer (B).
GMAT Rate Conversions
July 23, 2012
One of the simplest arithmetic rules is that when you divide something by itself, you get 1.
What’s 3/3? 1.
What’s x/x? 1
By the same logic, what do you get with, say, inches/inches?
That’s also equal to 1.
So let’s say that you need to find the number of seconds in 2 minutes. You can probably do this in your head! Multiply two by sixty and it’s 120 second. But have you ever stopped to wonder why that works? Well, you want seconds to remain, so you want to get rid of minutes—that means you want minutes on the top and on the bottom. You did the math instinctively, but if you had broken it down step by step it would look like this:
Minutes on top and bottom cancel:
Now, on test day you’d never go through all the steps just for something as simple as that last example. But that basic principle makes it easy to solve much more complex conversions on the GMAT. For instance, my car has a 17 gallon gas tank and gets 32 miles per gallon on the highway. If I’m highway driving at an average speed of 68 miles per hour, how long can I drive without needing to stop for gas? (Assume I don’t take bathroom breaks)
The question asks for hours. Once everything has canceled, we’ll be left with the unit we want on top–so to get hours on top, we start with the reciprocal of my speed:
Now, miles is extraneous. Since it’s on the bottom, we multiply by a proportion that puts miles on top:
Then, finally, to get rid of gallons, use the same strategy:
Most rate conversion problems in the GMAT quantitative section, however complex, function similarly. You’re just multiplying a series of fractions together—all that’s challenging is keeping the fractions the “right way” up so that you keep the units you want and cross of the units that you don’t.
Check out this video from our YouTube Channel for even more on the topic. Then try the practice question below. Good luck!
Question:
Magnabulk Corp sells boxes holding d magnets each. The boxes are shipped in
crates, each holding b boxes. What is the price charged per magnet, in cents, if
Magnabulk charges m dollars for each crate?
Solution:
Step 1: Analyze the Question
A complicated setup, with oodles of variables. Picking
Numbers will probably be a safe approach.
Step 2: State the Task
Our task is to calculate the price per magnet. The word per
signals a rate
Many GMAT word problems have wrong answers that can
be eliminated logically, and this is no exception. Since the
answer is the amount of money that each magnet costs,
we can be sure that the more dollars charged per crate (m),
the more money each magnet would cost. In other words,
the right answer would have to get bigger as m gets bigger.
Answers (A), (C), and (E) have m in the denominator, so
those expressions would get smaller as m gets bigger.
Those answers can be eliminated.
Step 3: Approach Strategically
We need to solve for “magnets” and “cents.”
What do we know about the number of magnets? Scanning
through the question stem, we find “Magnabulk Corp sells
boxes holding d magnets.” That means d magnets per box:
What do we know about boxes? “Boxes are shipped in
crates, each holding b boxes.” That’s b boxes per crate:
What do we know about the crates? “Magnabulk charges
m dollars for each crate.” That’s m dollars per crate:
And, of course, dollars convert to cents at the rate of
100 cents per dollar:
Then set up multiplication such that cents are in the
numerator, magnets in the denominator, and everything
else cancels:
That’s answer (B).
GMAT Test Day: What to Expect
July 21, 2012
“I knew it. We should have practiced with these helmets on. I hear Darth everywhere…”
Most students, after careful study, know what to expect on test day in terms of GMAT content. However, it also important to know what to expect when you arrive at the Pearson Center. Just as you have learned and practiced GMAT strategies, you should have a plan for handling your breaks and using your scratch sheets wisely.
When you first arrive at the Pearson Center, you will use your ID to check in and register a digital scan of the vein patterns in your palm. Afterwards, you will place all of you personal items in a locker. These include ID’s, watches, phones, wallets, keys, and even tissues. You will not be able to bring anything with you into the testing room. Furthermore, you will not be able to access these items during breaks in the test.
Once you are ready to get started, you will scan your palm at the door to the testing room, and you will be assigned a computer on which to take your exam. Any time you reenter the test room you will need to provide a palm scan to prove you are still the same person.
Once seated, you will begin the GMAT, but keep in mind that other test takers will not be starting at the exact same time as you. Some will be in the middle of their exams when you begin, and some may start after you. Furthermore, some test takers will be taking tests other than the GMAT. This means that everyone’s breaks will be at different times. While no one will talk in the testing room, be ready for people to move around while you are taking your exam. The proctor will offer you noise-canceling headphones when you arrive. These can help to minimize these distractions, but you may want to take one of your GMAT practice tests with headphones to get used to the sound of your breathing. It can be a bit distracting…kind of sounds like Darth Vader.
Your breaks will be 8 minutes long and are optional. This is a tricky move on the part of the test maker. We tend to have a sense of what 10 minutes feels like, but 8 minutes is a different story. Make sure you locate the bathrooms before you start your exam, so that you can find them quickly once you are on your break. The test will start without you if you are not back in time. Remember you have some time-consuming security hoops to jump through to get back to the computer, so make sure you don’t take too long of a break.
Finally, you will be given four bound, double-sided wet erase sheets and a wet erase pen. If you run out of room you can receive a new set of sheets; to do so you must raise your hand, and the proctor will bring a new set to you and take away your used set. Since this process takes time, you want to minimize how often you trade. The best move is to always trade during the breaks so that it doesn’t take up any of your test time. Additionally, you may want to switch sets once in the middle of the quantitative section. You should try not to trade out your scratch sheets during any of the other sections.
The vast majority of your prep time should be on GMAT content, but you don’t want to run into unnecessary test day stress because you are not ready for all of the rules at the Pearson Center.
GMAT Ratio Problems: Avoid the Algebra
July 14, 2012
Mastering ratio questions on the GMAT requires systematic organization of the individual pieces and a solid understanding of how ratios are typically presented and tested on test day. One of the most common presentations of ratios on test day is a question that presents a part:part or part:whole relationship and asks for the actual number of a part, the whole, or a difference between the parts.
The first thing to note about ratios is that they represent relationships between items. On the GMAT Quantitative Section, the ratio is usually in the simplest form; I call this multiple level 1 because it represents the smallest potential positive quantity for each aspect of the ratio. For instance, if a question tells you that the ratio of apples to oranges is 2:3, you know immediately that the minimum number of apples possible is 2 while the minimum number of oranges is 3 and the minimum total pieces of fruit is 5. Also, the actual number for those items must be a multiple of that minimum. Selecting the correct answer quickly on ratio questions commonly revolves around your ability to determine a multiple for one of the parts in a ratio relationship.
In order to manage all of the information in the question well, let’s pull out a tried-and-true tool, the basic chart. I know that most of us set up a proportion for these questions and solve algebraically. We absolutely can deal with ratios in a traditional math route through a proportion and algebraic equation; however, setting up the algebra traditionally leaves more room for error and can take a bit more time depending on the complexity of the question. The method is ultimately up to you, but in your GMAT prep you always want to learn to choose the most efficient and effective route for the particular question at hand. If you love the algebra, go for it (For those who want to avoid it more often, check out this additional GMAT strategy). In this post, I want to introduce and explain my favorite way to deal with this typical ratio question type – the ratio grid:
| Multiple Level | ||||
|
1 |
Step 1: Identify Ratio Parts
First, let’s take a look at the different pieces of data that can be presented in a ratio question. The first things to identify about the given ratio are the individual parts. In the example ratio of apples to oranges from above, we have a base ratio of 2:3. The stated parts of the ratio are apples and oranges, so we plug these into the chart with their respective minimums.
| Multiple Level | Part 1: Apples | Part 2: Oranges | ||
|
1 |
2 |
3 |
Step 2: Finish Level 1 Quantities
Next, finish out your base minimums, determining the minimum total by adding the minimum individual parts and determining the minimum difference by subtracting the smaller part from the larger part.
| Multiple Level | Part 1: Apples | Part 2: Oranges | Total Fruit | Difference |
|
1 |
2 |
3 |
5 |
1 |
Step 3: Strategically Eliminate
At this point, pause and eliminate answer choices strategically based on the minimums you have identified. The answer MUST be a multiple of the corresponding minimum that the question is asking for. Often this one step is the last thing that you will need to solve the question. For example, using our hypothetical apples : oranges scenario above, if a question asked for the total number of apples, eliminate anything that is not a multiple of 2 because the total number of apples must be some kind of multiple of 2. If the question is looking for the total number of oranges, eliminate all choices that are not a multiple of 3. If the question is asking for the total number of fruit in the basket, eliminate all choices that are not a multiple of 5 and so on. If that does not eliminate 4 choices, we move on to the next level to evaluate those choices that are left.
Step 4: Plug in the Actual Value From Question
In a typical ratio question, along with the base ratio, the test-makers will give you an actual total for one of the parts, the total, or the actual difference. Your task at this point is to plug the actual value in at the appropriate place in the chart and to determine which multiple level that actual value is sitting at. For instance, for our scenario of the apple to orange ratio of 2:3, if the question told you that there are 30 total pieces of fruit in the basket, we would plug 30 in below the original 5 and determine the multiple level by identifying what 5 must be multiplied by to get to 30. Since, 30 is 5 times 6, we are working on level 6.
| Multiple Level | Part 1: Apples | Part 2: Oranges | Total Fruit | Difference |
|
1 |
2 |
3 |
5 |
1 |
|
6 |
30 |
Step 5: Determine Your Answer
At this point you can solve for any of the remaining parts. For instance, if the question told you that in a basket the ratio of apples to oranges was 2:3 and the total pieces of fruit in the basket was 30 and asked for the actual number of apples in the basket, you would multiply 2 by 6 to get 12.
| Multiple Level | Part 1: Apples | Part 2: Oranges | Total Fruit | Difference |
|
1 |
2 |
3 |
5 |
1 |
|
6 |
12 |
30 |
Now, let’s walk through these steps using a realistic GMAT question:
The ratio of girls to boys in a class is 6:7. If there are 18 girls, how many total students are in the class?
A) 18
B) 21
C) 27
D) 28
E) 39
Step 1: Identify the Parts and Step 2: Fill in the Remaining Level 1 Quantities
First, look at just the base ratio to establish the minimums for level 1. The ratio of girls to boys in a class is 6:7.
| Multiple Level | Boys | Girls | Total Students | Difference |
|
1 |
6 |
7 |
13 |
1 |
Step 3: Strategically Eliminate
Because we are ultimately solving for the total number of students in the class, we need to eliminate anything that is not a multiple of 13, our minimum number of total students.
A) 18 – eliminate
B) 21 – eliminate
C) 27 – eliminate
D) 28 – eliminate
E) 39 – keep (MUST be the answer)
And we are done! Always check your multiples before you deal with the rest of the question. Sometimes, this is all that you need to correctly and strategically solve.
Let’s look at one more that is a bit more difficult.
Three investors, A, B, and C, divide the profits from a business enterprise in the ratio 5:7:8, respectively. If investor A earned $3,500, how much money did investors B and C earn in total?
A) $4,000
B) $4,900
C) $5,600
D) $9,500
E) 10,500
Step 1 & 2: Identify Parts and Finish out Grid
First we look at the base ratio to establish some minimums. Three investors, A, B, and C, divide the profits from a business enterprise in the ratio 5:7:8, respectively. In this chart, I modified the total column slightly because the goal of the question is to deal with the sum of B and C.
| Multiple Level | A | B | C | Sum of B and C |
|
1 |
5 |
7 |
8 |
15 = (7+8) |
Step 3: Strategically Eliminate
The goal is to solve for the sum of investors B and C, so the answer MUST be a multiple of 15. Eliminate every choice that isn’t a multiple of 15.
A) $4,000 – eliminate
B) $4,900 – eliminate
C) $5,600 – eliminate
D) $9,500 – eliminate
E) $10,500 – Keep – MUST be the answer
Let’s look at one last variation of this pattern.
At a certain zoo, the ratio of sea lions to penguins is 4 to 11. If there are 84 more penguins than sea lions at the zoo, how many sea lions are there?
A) 24
B) 36
C) 48
D) 72
E) 132
Steps 1 & 2: Set up the base ratio
At a certain zoo, the ratio of sea lions to penguins is 4 to 11.
| Multiple Level | Sea lions | Penguins | Total together | Difference |
|
1 |
4 |
11 |
15 |
7 |
Step 3: Strategically Eliminate
Since we are solving for the number of sea lions, eliminate any choice that is not a multiple of 4.
A) 24 – Keep
B) 36 – Keep
C) 48 – Keep
D) 72 – Keep
E) 132 – Keep
Step 4: Plug in Actual Value and Determine Multiple Level
“If there are 84 more penguins than sea lions at the zoo” is the given difference between the pieces. To get to 84 you must multiply 7 by 12, so we are at multiple level 12.
| Multiple Level | Sea Lions | Penguins | Total Together | Difference |
|
1 |
4 |
11 |
15 |
7 |
|
12 |
84 |
Step 5: Determine your answer
Since we are looking for the number of sea lions, multiply the base 4 by the multiplier 12. Therefore, “C” is our final answer.
| Multiple Level | Sea Lions | Penguins | Total Together | Difference |
|
1 |
4 |
11 |
15 |
7 |
|
12 |
48 |
84 |
The big takeaway for ratio questions on the GMAT is that most are about multiples. Make sure that you check multiples before you waste too much time walking through the problem completely. Also, organize your information systematically on test day to efficiently and effectively walk through every question on the test.
Do you have a favorite way to approach these questions? Post it in the notes so that we can all check it out.
