Two Types of GRE “Averages”: Mean and Rates

The word “average” on the GRE can refer to two concepts: arithmetic mean, and the average speed (or average rate) formula. It’s important not to confuse the two on the Test Day, as they require different formulas to solve.

Mean is the mathematical average. This is defined as the sum of the terms divided by the number of terms. Mean = Sum / # of terms. For a list of consecutive integers or evenly spaced numbers, the mean is equal to the median, or the middle number. For example, the “average” of 3, 5, and 9 is 5.67.

Average Speed or Average Rate is often found in complex word problems. This type of question is one many students are less familiar with so you may not have seen it before. Let’s review two important equations to remember and look at how this concept appears on the GRE.

The first formula to memorize is: D = R x T. This stands for Distance = Rate x Time (referred to as the “DIRT” formula). It is perfectly acceptable to also think of it as Time = Distance / Rate or as Rate = Distance / Time as well. Usually the “Rate” is speed but it could be anything “per” anything. In a word problem, if you see the word “per” you know this is a question involving rates.

The second formula is: Average Rate = Total Distance / Total Time. This is its own special concept and you will notice that it is NOT a simple Average of the Speeds (which would be something like the Sum of the Speeds / the Number of Different Speeds or what we know as the Arithmetic Mean). Average Rate is a completely different concept, so do not let the common word “average” confuse you. Let’s look at a sample question from Grockit’s GRE question bank:

Question 1: The average (arithmetic mean) of four numbers is 30, after one of the numbers is removed, the average of the remaining three numbers is 10. What number was removed?

We know that the four original numbers sum to 30*4 = 120. The new equation becomes:

4*30 – x/3 = 10
120 – x/3 = 10
120 – x = 30 (add an x to each side and subtract a 30)
90 = x

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Learnist: How to Achieve Perfect Pacing on the GRE

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. You can download TWO FREE GRE practice tests at gre.org!

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. If you feel up to the challenge, Major Tests.com offers 7 free GRE reading comprehension practice tests with explanations.

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 parts:

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.
Around 34 minutes, you should be around question #20

Review some basic Quant tops on this blog before you attempt you next full-length exam. A combo of great benchmarks and strong content knowledge will help you move quickly and confidently through each section.

Check out more tips for GRE pacing on this Learnboard!

Learnist: 7 Ways to Rock the GRE’s Quantiative section

Each GRE quantitative section consists of 20 questions to be completed in 35 minutes. Here’s how to get the most points possible!

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.

Review the allowable functions here on the GRE’s official website‘s instructions for using the calculator!

Check out more ways to rock the GRE’s Quantitative section on Learnist!