Is that a comparison?

One way to classify conclusions on GMAT Critical Reasoning conclusions is comparative versus absolute.  Why should you care about this classification?  Because this distinction can be very helpful in eliminating wrong answers and finding right answer.

A comparative conclusion will make a comparison between two or more groups.

Car A is better family car than Car B.

An absolute conclusion will just express an opinion about one specific topic or situation.

Therefore, A monorail should not be installed in Town C’s central district.

As a start, let’s get used to classifying conclusions as absolute or comparative.  If the conclusion is comparative, identify the two groups being compared.

1) Therefore, children in the United States who spend at least two hours a day outdoors are less likely to be obese than other children.

2) Thus, Springfield’s recycling program is likely to achieve its aim.

3) For these reasons, isolationism should not be considered a viable trade strategy.

4) The service sector will become more important to Caloda’s economy in the future.

5) Brand D is the best brand of vacuum cleaner available.

(See bottom of this post for answers)

Now that you are comfortable identifying different types of conclusions, we will consider how this classification will help you find the right answer. In many critical reason question types, your job in finding the answer is to influence the conclusion (strengthen the conclusion, weaken the conclusion, find the assumption).  Let’s consider answer choices that are most likely to influence these different types of conclusions. Read more

Data sufficiency question are a strange animal that exists only in GMAT land.  The newness of this question type creates high levels of anxiety because we don’t know how to react when we see something new (How do you think you would react if you were standing face to face with a unicorn?).   Once we get over this newness, data sufficiency questions all follow a specific morphology, and in my opinion actually contain less diversity than problem solving questions.  There is always either a yes/no question (is ab even?) or value question (how many boys are in the class?), followed by two statements, and the five answer choice are always the same and in the same order. (If you are completely unfamiliar with data sufficiency questions take a look at an example here)

Because of this very confined structure, there are actually cases where the structure of question and statements can give you information regardless of the specifics of the problem. There are at least four instances where a specific form of the statement(s) will allow you to eliminate several responses without evaluating the full content of the problem.

1) A value statement for a yes/no question

If a statement provides a value for the sole variable in the question, it is definitely sufficient to answer any yes or no question.

For example:

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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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We’ve heard the expression Don’t reinvent the wheel. There is no need to start from scratch every time you undertake a task.  The same reasoning applies in many ways to GMAT problems.  In fact, this logic is exactly why doing practice problems is a valuable tool for improving your GMAT score.  If you have seen a similar problem before, you will probably have a jumping off point for that problem on the actual GMAT.

While focusing on efficiency is important on the GMAT, in some cases it can be problematic to rely on traditional rules of thumb.  The GMAT is good at finding and testing the exceptions to rules that apply in many cases.  For example, the adage it takes two equations to solve for two variables is not true in all cases.

One common shortcut of thinking is the assumption that to show the converse of a statement you need exactly the opposite information.
That is: If in order to prove x, I must know y and z are true then in order to prove the opposite of x I must know that y and z are false.
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How do you feel when you see a sentence correction with a very substantial underlined section? Overwhelmed, anxious, perhaps even a little bit angry.  Maybe at this point you move to freak out mode thinking I am never going to complete this problem in 1 minute and 15 seconds (recommended average time for sentence correction problems).  I have found that freaking out is never the optimal approach to any GMAT questions, so let’s identify some alternate approaches we can use to our advantage when facing a sentence correction problem with a lot underlined.

1) Lots underlined usually means lots of mistakes.  When a large portion is underlined, there are almost always several mistakes in the sentence, and thus several different ways to get to the answer.  Don’t feel like you have to comprehend everything that is going on in the sentence right away, but rather start with the grammatical principle with which you are most comfortable.  I actually dislike problems with only a few words underlined because these problems often involve only a single issue “ and if I don’t know that particular rule I am in trouble.

2) Use your initial read of the sentence as a jumping off point. Often you may spot an error in the initial sentence.  Instead of trying to completely scan all the answer choices, immediately go to this particular area in each answer choice to see if the problem still exists and eliminate accordingly.
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Invariably when I ask a student what about their strengths and weaknesses related to the GMAT, his list focuses on topics or question types.

• I struggle with the quant section.
• Sentence correction is my best verbal question type.
• I hate data sufficiency.
• I’m good at rate problems, but I can’t figure out probability.
• Etc.

Now, the ability to generate this sort of inventory is important. You should generally devote more study time to those topics and question types where you are weaker. But along with this topic-based inventory, other aspects of your personality and approach will impact your GMAT experience. Understanding these underlying tendencies in yourself can be invaluable to improving your GMAT performance.

In each of the four cases below consider which statement sounds more like you.

1) To solve a challenging problem
A. Give me a formula. Give me an algorithm. As long as I know an approach I can crank through the math and get the problem done.
B. I like the chance to get creative. Drawing diagrams and recognizing patterns is what I do best.

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Take a look at the following problems.

Data Sufficiency: What was Company X’s percentage profit in 2011?

1) The ratio of costs to profits for Company X was 3 to 1 in 2011.

2) Company X’s costs in 2011 were $360,000.

A recipe for punch calls for 4 parts seltzer to one part juice. If John wants to make 5 gallons of punch, how many 8 ounce cans of juice does he need (1 gallon = 128 ounces)?

A) 32

B) 20

C) 16

D) 10

E) 8

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When not providing insight into the fascinating world of the GMAT, I enjoy watching detective shows on television.  In many episodes, one of the detectives must delve into the mind of the perpetrator “ actually try to think as the perpetrator does.   In so doing, the seemingly random clues come together (often via a slow motion or black and white flashback scene) leading to an insight that breaks the case.

I am going to advocate taking on this television detective mentality in approaching GMAT problems.  Perhaps there is a further parallel as the mind of the GMAT question writer may seem to be just as scary a place as the mind of a criminal. But the ability to think like a GMAT test writer can provide multiple benefits including enabling you to get more questions right and allowing you to have more confidence in your answers.

So let’s try think about three lessons we can take from our favorite crime dramas and apply to the GMAT.

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Given the statement, the ratio of men to women in the room is 3 to 5, how many men are in the room?

You probably recognize pretty quickly that it is not possible to answer the question above.  Just given a ratio, it is not possible to identify the actual number of men in the room.  At this point we know the number of men in the room must be a multiple of 3, but the actual number could be 3 or 3,000 (although I am not sure I have been in a room that large).

Along with ratios in their traditional form (3 to 5 or 3:5), there are other types of numbers that are ratios, slightly disguised

a) Fractions: The container is 2/3 full.

This statement is expressing that there are 2 full parts for every 3 total parts of the container (a ratio of 2 to 3).

b) Percentages: 33% of company employees have Master’s degrees.

This statement is expressing for every 33 employees with Master’s degrees there are 100 total employees (a ratio of 33 to 100).

c) Percentage or fractional increase: The company’s profits increased 25% (or ¼) from 2010 to 2011.

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When do you leave the house without directions? Or perhaps the more modern reference, is when do you start on your way without plugging in your destination into a GPS device? I expect the answer for most of you is when I know where I am going.

Conversely, when you have no idea when you are going, your solution is most likely not to get in your car (or on your bike or public transit) and just start randomly driving around hoping you run into your desired destination. Ideally, you probably look up where you are going and plan out a route. Alternatively, you might know a nearby destination and start heading there (e.g. I know the bike store is near that place I get coffee). Finally, on occasion you may just head to an area where you expect to find a type of business (e.g. Gas stations are usually close to freeway entrances).

Now, all this talk about directions has been fun, but let’s bring the analogy around to GMAT quant problems. Sometimes when you see a GMAT problem, you may understand what the question is asking and see the path to the solution. In these cases, dive right in. Start driving and you are likely to reach your destination because you know “ or at least have a good sense “ of where you are going. Read more