Tag Archives: Quantitative Section

Week 3 – Does Data Sufficiency make your head spin?

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As a contact-lens wearer, I occasionally have a rough morning when I put my contacts in the wrong eyes, mixing up left and right. This leads to an unpleasant few minutes where I can’t focus and my blurry vision starts to give me a headache. For me, the Data Sufficiency Questions on the Quantitative portion of the GMAT make me feel like I put my contacts in wrong. These questions are uncomfortable, annoying, and usually headache-inducing.

Not sure what a data sufficiency question is? Here’s an example:

If x is a positive integer, is x divided by 5 an odd integer?
1.)     x contains only odd factors
2.)     x is a multiple of 5

A)            Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B)            Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C)            BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D)            EACH statement ALONE is sufficient.
E)             Statement (1) and (2) TOGETHER are NOT sufficient to answer, and additional data is needed.

But, given that Data Sufficiency Questions will make up about 38-40% of the 37 Quantitative section questions, there’s no getting around these ones. From lots of practice and lots of missed questions, I’ve tried to learn from my mistakes:

Mistake #1: Reading the answer choices (A,B,C,D,E) – there’s not time! gmatblurry

Since all data sufficiency questions have the same answers, there’s no use reading them each time. I’m making sure that I know the answers and what they mean beforehand. Also, to avoid confusion and overwhelming myself with answers, I always start by setting myself up for process of elimination. For each D.S. question, I write 12TEN on my scratch pad. From there, I approach each statement and cross off answer possibilities as I go.

1 (Statement 1 only)
2 (Statement 2 only)
T (Together- both statements sufficient)
E (either statement alone sufficient
N (Neither)

You learn quickly that you can start crossing out answers as you evaluate statements. (For instance, if Statement 1 doesn’t work, you can cross off 1 & E).

Mistake #2: What is the question stem asking?

I always have to ask myself this it seems. Maybe with the time pressure, I feel like I need to go quickly onto the problem choices. There’s information in the stem that needs to be dealt with first though. Before you begin, ask if you’re looking for a Yes/No answer (i.e. is X=25) or a Value (what is x equal to?) This helps set the course so you know how far to solve. Which leads me to my next mistake:

Mistake #3: Don’t solve if you don’t need to!

My whole life I’ve been solving to the end of problems. I see an equal sign and a math equation and look for that one final number. In D.S. problems, many questions are just looking for the ability to answer. For instance, if a question asks “What is the value of x?”  and you have simplified an equation down to:  502x = 1975 – 2(20) , don’t waste time calculating for x. You know you can arrive at x, which is what the question is asking for. The correct answer would be how many statements you used to arrive at the final equation.

Mistake #4: Watch out for statements that give no new information.

Take this question for example:

Company X has a total of 400 employees. (addit’l information in question)…. What percentage of Company X employees received a raise?

1) 80 of Company X’s employees are managers.
2) 320 of Company X’s employees are not managers

Warning bells should be going off in your head right now. Even though the two statements are worded differently, they present the exact same information (giving numerical data on how many managers/non-managers are in the employee group). Don’t be fooled by the same statement simply re-packaged in a different format.

If all else fails with Data Sufficiency questions, and you’re simply stuck in a rut, take an educated guess. Hopefully though, by mastering some of your mistakes, you won’t have to resort to that. Good luck!

Week 2- Quantitative Section Studying: Where’s the Calculator?

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Last week, I kicked off my 8 week GMAT journey with some tips on registering for the test and getting your study schedule planned out. For Week 2, it was time to dig in and start studying full force!

I began with a quick glance through the my prep book and then took one of the in-book practice tests. If you need a hit to your confidence, this is the way to start! Besides being perplexed and wrong on many answers throughout the test, jumping right into a practice round was a great introduction. Rather than reading about the format of the questions and the content of the test, I could see for myself what a typical test included. The practice run gave me a good idea of my strengths and weaknesses, and thus gave me a road map for my study strategy.

From the initial practice test, I found that my weakest area was the Quantitative portion of the test. I decided to focus my initial attention for the next 2-3 weeks on this part of the test, adding more time if needed. calculator

In talking with applicants about the Quant section, I try to warn people that they are not able to use a calculator on this portion of the test. That point never quite hit home until I started doing the math myself. Though the test writers keep the numbers fairly small and manageable without a calculator, I never quite realized how much I rely on mine for basic math. My speed calculations are going to have to improve over the next few weeks, as well as my memorization of formulas and arithmetic rules. It’s amazing how fast those skills go when you’re not using them every day!

As I’m working through the prep book and example questions for the math section, there are a few tools that have been pretty helpful:

  • Error Log: What do the following have in common? Nested functions, Rules of Radicals, Combinations and Probability, Combined Work Formula, Mixture Problems…?  They’re all topics that have tricked me thus far on the GMAT. I keep a fairly detailed record of the questions I miss in the practice problems, or the topics that I can’t even remember learning about (did I miss a whole month of math in high school?) This is called an “Error Log” and it’s a recommended tool to refer to as you study and prepare. Some people keep a detailed spreadsheet with analysis of every question they get wrong. For me, I simply keep a running list in the back of my prep book, with page numbers and what I did wrong for each problem. I plan to look back on this, especially in the final “crunch time” days, to make sure I don’t repeat errors on my test day. Always remember to learn from your mistakes!
  • Daily GMAT Problem: Yes, there are some days where I might not get to my studying until late at night, or maybe not even at all that day (I’ll make it up- promise!) But every day, the least I can do is answer one GMAT question. I signed up for Beat the GMAT’s Daily Math Question (Verbal Questions are also available for my later studying) that gets e-mailed to me every morning. Whether it’s staying an extra 5 minutes after work or completing the question on my lunch break, I make sure I answer the question every day. Some days it’s a confidence boost to know the answer, but other days, I learn something new. Either way, it’s a good way to fit the GMAT into your day.
  • Quantitative Formula Sheets: Quick- what’s the equation for the area of a trapezoid? 2 weeks ago, I couldn’t even begin to tell you. Now, it’s one more formula that I’ve started to memorize. And there’s no way around it… you have to memorize them. For me, seeing all the formulas in one condensed place is more convenient than hunting through a giant book. Also, this way, I can slip a sheet into my purse and memorize when I have 5 minutes free. While you can certainly make your own “cheat sheet” or buy a pre-made version, there are plenty of free online versions also. One of my favorites comes from PlatinumGMAT, but there are also many options on the GMATClub Forums if you look around.

I’m going to keep chipping away at these math problems, but let me know if you have another tip for the Quant section!

And PS- the area of a trapezoid is area_trapezoid2, in case you needed to know.