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Quantitative Posts

Understanding Ratios & Proportions on the Revised GRE

By posted May 23, 2012

Time management is crucial for great scores on the GRE Test, and one way to improve your pacing is to become faster at some of the more accessible skill tags. Ratios and proportions are the basics of algebra, and better scores with this concept will help you get harder GRE Quantitative questions correct! Let’s review the fundamentals!

Already a Ratios & Proportions rock star? Check out your percentage correct for these type of questions on your personal profile on Grockit.

A ratio is a comparison between two quantities. It is usually expression as a fraction (x/y) or with a colon (x:y), or in a word problems (“the ratio of apples to oranges”). Typically, whatever follows the word “of” is in the numerator, and whatever follows the word “to” is in the denominator.

A proportion is a set of ratios set equal to each other. Basically, an equation with two fractions, such as 4/x = y/7. You can always solve a proportion by cross-multiplying the numerator of one fraction by the denominator of the other. 4/x = y/7 would become 28 = xy after we cross-multiplied.

Check out a sample ratios and proportion question by creating a Custom Game in the Grockit lobby and selecting that skill tag.

Ratios are usually expressed as part: whole or part:part. Making that distinction is important, especially in complex GRE word problems. Ratios are always reduced to the simplest form, but you can multiply them by any integer to increase the numerator/denominator values, as long as you do the same thing to the top and the bottom of the fraction. Read more »

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GRE Multiple Choice – Select One Answer: The Perfect Strategy

By posted May 21, 2012

Problem Solving is the classic GRE Quantitative question-type, and the “select one answer” is the one format that has not changed from the old GRE to the Revised GRE. Like any standard Quant question, you will be presented with a typical math problem, given five answer choices, and told to select only one choice. Here is the step-by-step strategy to improve your accuracy on these seemingly straightforward questions.

Step 1 – Write down what the question is asking. This is especially important for long word problems. Don’t start solving unless you know what you’re solving for. Is the question looking for the area of a circle, or just its diameter? X, or 1/X? Part of a ratio, or the entire ratio?

Need more help with GRE Test Day strategy? Contact one of Grockit’s GRE tutors to set up a private tutoring lesson!

Step 2 – Extract any given information. As you read the question, pull out any definitions (“x is an integer,” “the set contains only primes,”etc.), or numerical relationships (z < 13, y = -1/2x + 14, etc.). Write them down in shorthand.

Step 3 – Examine the answer choices. What are they? Numbers, variables, words, or some combination? What does that tell you about the question? Can you potentially pick numbers or backsolve (plug-in)? If you had to guess strategically, are there any answer choices that seem illogical based on the definitions and numerical relationships established by the question stem? Any odd “outliers,” or answer choices that are suspiciously different from the rest?

Step 4 – Select your strategy and solve. There are only 4 ways to solve: Do the Math, Backsolve, Pick Numbers, or Guess Strategically. Based on the answer choices and your overall pacing within the Quantitative section, select the strategy that feels right to you, and go for it! Don’t second-guess yourself, or spend too long considering which way is “best.” Many GRE questions can be solved in more than one way, but you don’t get extra points for knowing that.

Step 5 – Double check your answer. Are you really done? Did you find what the question was asking? Before you confirm your answer, just make sure you didn’t skip a final step. The “second-to-last” step is frequently an incorrect answer choice on GRE questions.

Now that you understand the basics of Multiple Choice – Select One strategy, practice some questions on Grockit to raise that Quantitative score!

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Top 5 tips for multiple choice success on the GRE

By posted May 17, 2012

Looking to apply to graduate school and get your masters degree to further your career?  An important piece of your application is your score on the GRE test.  Practicing for tests should always involve learning strategies to approach that specific test with.  The new GRE has some new twists to the multiple choice section that you should be aware of as you study and take the GRE test.

1. Notice which type of multiple choice question you are dealing with.

The GRE has some typical multiple-choice questions with five answer choices and one correct answer.  However, there will also be questions with more than one right answer.  The quickest way to distinguish between these two question types is to look at the letters of the answer choices.  If they are inside a circle, there is one correct answer.  If they are inside a square, there could be more than one correct answer choice.  However, still pay attention to the directions because sentence equivalence questions have exactly 2 right answers, while other squared answer choice questions could have 1 correct answer choice or up to several correct choices.  Familiarity with the different question types and directions through lots of practice is the sure-fire way to avoid missing questions because of marking the wrong number of answer choices.

Test your GRE skills with this GRE reading comprehension detail practice question.  Read more »

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Top Ten Ways to Handle GRE Timing on Practice Tests

By posted April 24, 2012

To ace the GRE, you need to ace timing. The best graduate schools want grad students who can pace their time well. Graduate school candidates with good GRE scores know how to organize their GRE test prep, use the best GRE resources (both free GRE practice questions like those at ETS’s website and supplemental books and online GRE practice questions), and can pace themselves effectively within each section of the GRE.  Use the free GRE practice tests offered by ETS (the Powerprep software) to practice these free pacing tips. More free GRE practice tests are offered on the websites of almost every major GRE test prep company. Your dream college is only a couple month’s hard work away!

  1. Answer every single question on your practice tests. Finishing all sections is essential to a high GRE score.  Even if you come to the end of a section, and realize you have more questions than you have time to work on, make sure to click an answer for each one before the time runs out. This discipline on your GRE practice tests will set the right habit for Test Day, even if it’s painful at first to answer questions you can’t solve quickly.
  2. Write down what the question is really asking. For GRE multiple choice Quant questions, there is often an extra step required to solve. For example, it may ask for “the smallest prime factor of y” rather than just “y.” Answer choices that look “obviously” right for easy questions are likely correct. Answer choices that look “obviously” right for difficult questions are likely incorrect.
  3. For Verbal, save time for Reading.  For each Verbal section, you will have approx. 20 questions to answer in 30 minutes. This is approx. 1.5 minutes per question. But remember, that you’ll need a few extra minutes for Reading, so try to do the Text Completion and Sentence Equivalence questions in less than that time. Try to do pacing drills where you work on doing them in 1 minute each. Don’t rush and lose accuracy, but remember the importance of finishing the entire section.
  4. Create benchmarks for Quantitative. The Quant sections of the GRE will each contain approx. 20 questions and you will have 35 minutes to answer them. That works out to 1.75 minutes a question. Divide the section into 4. Around 9 minutes, you should be on question #5. Around 18 minutes, you should be on question #10. Around 26 minutes you should be on question #15, and around 34 minutes, you should be around question #20. Read more »

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Top Ten Most-Tested GRE Math Concepts

By posted April 20, 2012

The quant section of the revised GRE Test may have slightly changed format-wise, but the difficulty level of the GRE questions themselves have not. To get better GRE scores and get into the best graduate schools, you’ll need a strong understanding of the underlying math concepts: arithmetic, algebra, geometry, and data interpretation. Even if you’re good at Quant, a little basic review is a great refresher. Even singers like Katharine McPhee or Christina Aguilera warm up with scales! J Many of these concepts can be practiced for free online on sites like Grockit which offer free GRE practice questions.

1.  Number Properties. The properties of odds and evens, integers, fractions, positives, and negatives will all appear in various questions on your Revised GRE test. This is especially tested on Quantitative Comparisons. Variables can be negative integers, negative fractions, zero, positive fractions, or positive integers – don’t ever make assumptions!

2. Plane Geometry. Triangles are the most-tested shape on the GRE. You should know the Pythagorean Theorem, Triangle Inequality Theorem, the special right triangle ratios (45-45-90 and 30-60-90), as well as the properties of isosceles and equilateral triangles. Also review the types of angles, circles, and polygons.  Make sure you know how to find the perimeter, area, and volume of these shapes.

3. Word Problems. The GRE Problem Solving questions often contain challenging word problems – you’ll need to know how to “translate” English to Math.

Practice these three initial concepts in Grockit’s question bank here.

4. Rates & Work. The most important need-to-know formulas on the GRE are D = R x T, Distance = Rate x Time, and the concept of Average Speed. Average Speed = Total Distance / Total Time.

5. Probability. The probability of an event occurring is the desired outcomes/total possible outcomes. The probability of two events occurring together is the product of the two probabilities. Memorize the combination and permutation formulas. Combination: n! /n-k! k! Permutation: n! / n-k! Read more »

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Sequences on the GRE

By posted April 2, 2012

On the GRE, there are two types of sequences to watch out for: arithmetic, and geometric. An arithmetic sequence occurs when there is a constant difference between terms. For example, in a sequence of 3, 5, 7, 9…, then the difference is +2. In a geometric sequence, there is a constant ratio and not a constant difference. The common ratio is found by dividing the 1st term into the 2nd term. For example, in a sequence of 2, 4, 8, 16…, the ratio is 2, since each term is multiplied by 2 to get the next term.

Need more help with sequences? Contact a Grockit GRE Tutor to set up a 1-hour Quantitative lesson. Review strategies for each question type, isolate your strengths/weaknesses, and build your content knowledge before Test Day!

The concept of sequences is fairly simple, but what to do when a question asks for an impossibly high term, such as the 149th term? There isn’t enough time to write the sequence out that far, so we’d use one of the following formulas:

For Arithmetic: an = a1 + (n – 1)d

For Geometric: an = a1 * r(n-1)

In these equations, an = nth term, a1 = first term in the sequence, d = difference, r = ratio, and n = the number of the term you want to find. For example, if we were asked to find the 33rd term in the geometric sequence above, we would plug in as follows:

an = 2 * 2(33 – 1)

an = 233

Let’s look at a Grockit practice question:

1. In the sequence of numbers, a1, a2, a3, a4, a5, each number after the first is 5 times the preceding number. If a4 – a1 is 93, what is the value of a1?

For this question, it is best to choose simple numbers to see the pattern. If a1 is 1, then we know that a2  = 5, a3  = 25 and a4  = 125, so we know that a4 will be 5*5*5 or 125 times the value a1,. No matter what we choose as a1, a4 will always be 125 times greater than a1. We need to find a value such that 125x – x = 93

124x = 93

x = 3/4

Ready for more practice? Check out the new Revised GRE lobby in Grockit – study with other students, and ask for help when you need it by clicking the blue “Ask for Help” button. The best way to learn is together!

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Top Ten Things to Know About Your GRE Score

By posted March 29, 2012

The revised GRE has an entirely new scoring system, which you need to understand to get a good GRE score. Practicing free GRE test questions on ETS’s official GRE website or on Grockit is a great way to familiarize yourself with the content, but you’ll also need a comfort-level with the revised format to take a bad GRE score to a good GRE score. Here are the top ten things you’ll need to know about the new GRE scoring to add a great GRE score to your graduate school application.

  1. The AWA scoring is between 0-6. This remains unchanged from the old GRE. You’ll still writing two essays, which will be scored in .5 increments by two graders. You will receive “NS” or no score, if you do not type any text. You will receive 0 if you write in a foreign language, or completely off-task.
  2. Verbal and Quantitative are on a 130-170 scale. The scaled score on the GRE is the most noticeable difference between the older GRE and the revised GRE (as of August 2011). The scaled score is in increments of 1 point. (Previously, the GRE scaled score was between 200-800).
  3. Official scores will be received 10-15 days after the test. On Test Day, you will be an “unofficial” score, but you can view your official scores a couple weeks later for free online by creating a “My GRE Account” here.
  4. It costs $12 to get your score by phone. If for some reason you cannot create an account online, you can call 1-609-771-7290 or 1-888-473-7267 toll free and pay the $12 by debit or credit card. It’s much easier to create the “My GRE Account” if you can! Read more »

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How to Solve Rates & Work Questions on the GRE

By posted March 26, 2012

On the Revised GRE, Rates and Work questions may appear in any of the Quantitative question formats: Multiple Choice, Numeric Entry, or Quantitative Comparisons. A “rate” is anything per anything (miles per hour, laps per minute, gallons of paint per square inch of wall, etc.).

If you have trouble with these types of questions, you can set up a private tutoring lesson with one of the Grockit GRE tutors. Sessions are only $50/hr and are conducted via Skype using Grockit’s free GRE practice questions.

In the meantime, here are two formulas you should memorize to get these types of questions correct on your GRE test:

The first GRE formula to memorize before your GRE test is: D = R x T. This stands for Distance = Rate x Time. It can also be rearranged as Time = Distance / Rate or as Rate = Distance / Time.

The second formula you’ll want to know is: Average Rate = Total Distance / Total Time. Average Rate may have the word “average” in it, but remember that this is an entirely different concept from mathematical mean. Let’s look at an example question:

QUESTION 1: Joanne started her truck and drove 80 miles to see her mother. It took her 4 hours to get there. Then, she left her mother’s and drove another 40 miles to visit her aunt, but this time went 40mph. What was her average speed for the whole trip?  Read more »

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Top Ten Math Strategies for Better Scores on the GRE

By posted March 19, 2012

Even if you aren’t a math genius, better GRE scores and the best graduate schools are within your grasp! As you build your content knowledge for the GRE test, you will need effective GRE strategies to help you get the best GRE Quantitative score possible. Here are ten tips and proven GRE strategies that will take your GRE practice to the level of the highest-scoring GRE graduate student. Try them out on your next free GRE practice test! The Powerpreps from ETS are two free GRE practice tests you can download right now to get started!

Put these strategies to use with this GRE absolute value practice question.

  1. Slow down on Word Problems. Make sure you really understand the concepts underlying the question. One or two words can radically change the meaning. Don’t rush these challenging questions, even if the math seems fairly obvious; you’ll need to spend some time familiarizing yourself with “English-to-Math” translation tables.
  2. Use the calculator judiciously. When you practice for the GRE, avoid using a calculator unless you really need one. Most GRE Quant questions can be solved within 1-3 minutes without one. It’s provided on the GRE and allows for simple calculations, but don’t use it as a crutch. You should only need it for a couple of questions. You’ll save time if you can do simple conversions in your head.
  3. Plan to spend no more than 2 minutes per question. Each Quantitative section has approx. 20 questions and you are given 35 minutes in which to complete them. Some questions you will be able to solve in 1 minute, and some will take 2. If you’ve already spent more than 2 minutes on a question, guess strategically and move on. Read more »

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Top 10 ways to study for the GRE in 30 days

By posted March 13, 2012

Some people have more time to prepare for the GRE than others.  Preparing for tests is always stressful, but when you have just a month before your GRE test, it can feel like nowhere near enough time.  Don’t worry!  If you follow these 10 tips for studying for the GRE in 30 days, you will be able to make the most of your potential and get into grad school!

1. Make a study plan. - Since you have a relatively short period of time to prepare for the GRE, it’s essential that you get organized by creating a study plan.  Write down on your calendar which subjects you are going to study on which days, as well as the time you plan to study.  While you may have to adjust the times as other things come up, setting a certain time makes it more likely that you will stick to your plan.  Also, add to your calendar any full-length practice tests you plan on taking.  With a month until test day, you probably want to study 6 days a week for about 2 hours per day.  Don’t be afraid to give yourself that weekly day off so you don’t burn out!

2. Start with a practice test. - The first thing you want to do is assess your level on each section of the test by taking a full-length practice test.  This will also give you an idea of what it’s like to take a test on the computer, as well as the GRE structure and format.  ETS.org provides a free practice test.  Review the directions for the different question types beforehand so you don’t miss questions unnecessarily–some questions have more than one correct answer.

3. Mix it up. - If you plan on studying for 2 hours, break up your time into different subjects.  This will make time go faster and also ensure that you don’t study one of the sections too much.

Try this GRE algebra practice question and see if you’re ready for test day!

Read more »

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