GRE Exam: A Simple Guide To Solving Data Interpretation Problems

How to answer Data Interpretation questions

Data Interpretation questions present you with one or more tables, charts, or graphs, and ask you to make calculations and inferences based on this information. Most of the time, the questions will appear in graphs in one of three forms: bar graphs, circle graphs, or line graphs.

Each Quantitative Reasoning section will have three Data Interpretation questions. The tables, charts, and graphs will appear either at the top or to the left of every corresponding question.

The math on these questions is fairly straightforward; the difficult part is fully comprehending the information in the charts and answering the questions quickly and efficiently.

Most of the questions will test concepts that you should be familiar with: fractions, decimals, percentages, ratios, averages, probability, and, occasionally, geometry.

Since these topics are already known to you, the key to doing well on these questions is to fully understand the data so that you use the proper information to answer the questions.

Though your calculator will certainly come in handy on many of these questions, Data Interpretation questions are designed to test your estimation and approximation abilities, so you would be well-served to practice these questions with and without a calculator.

The two graphs and three multiple-choice questions following them illustrate a typical Data Interpretation question group and will form the basis of this overview of Data Interpretation strategies and methodology:

1.   For which year was the percentage change in revenue from the previous year the greatest?
2003
2004
2008
2009
2010

For this question, indicate all of the answer choices that apply.

2.   For which of the following years was the revenue from computers greater than in the previous year? (A) 2004 (B) 2005 (C) 2006 (D) 2008 (E) 2010
For this question, write your answer in the box.

3.   During the period from 2006–2008, what was the average annual revenue from phones? Round your answer to the nearest $100,000.

The first step to understanding the data is to note the title of the given graph. The first graph provides you with the annual revenue for a company from 2003–2010. Notice that the title tells you that the data is in millions of dollars. Thus the numbers on the y-axis represent millions of each labeled quantity.

The second graph provides you with the breakdown of the company’s annual revenue by product sales. Make sure to understand the legend and to understand how to read each bar.

For example, you should note that even though the top bar of the Computers component of 2003 ends at ≈45, computers did not account for 45% of that year’s revenue since the bottom bar ends at ≈22. Thus computers accounted for ≈(45 – 22) = ≈23% of that year’s revenue.

How to Answer Data Interpretation Questions

When answering Data Interpretation questions, you will want to keep a few principles in mind.

- Principle 1: When possible, you should estimate. Many of the questions you see in Data Interpretation will use words such as approximately or closest to. When you see these words, the test-makers are essentially telling you that you are not expected to arrive at a precise value. Instead, make sure that you stay roughly within the range of the given information, and the answer you arrive at will almost always be near only one of the choices. This strategy is particularly helpful in situations with bar graphs, where it might not be quite clear whether, for example, the review in 2003 is $38 million or $39 million. The short answer is that it does not matter. Stay within reasonable estimates, and the correct choice will still be obvious.

- Principle 2: Don’t confuse percentages, averages, and numbers. Question 1 asks you to determine which year had the greatest percent change from the previous year. You should first recognize that the years with the greatest absolute change from the previous year were 2003 and 2010. You may then be tempted to select 2010 since the absolute difference between 2009 and 2010 is greater than the absolute difference between 2003 and 2004. But recall from the percentages guide that percent change depends on the original value. Since the revenue in 2003 is so much less than the revenue in 2009, the percent change from 2003 might be greater than from 2009, even though the absolute change is less.

Thus you should calculate the percent change for those two periods (keeping in mind the importance of estimating!):

Percent change from 2003 to 2004: The revenue in 2003 is roughly $37 million and the revenue in 2004 is roughly $64 million.

The percent change is thus: .

Percent change from 2009 to 2010: The revenue in 2009 is roughly $75 million and the revenue in 2010 is roughly $44 million.

The percent change is thus .

Thus the correct answer for Question 1 is B.

- Principle 3: Use your eye. Unless noted otherwise, the diagrams are drawn to scale. This is helpful since you can minimize calculations when you are comparing choices or elements of a graph.

For example, in Question 2, you can determine all of the correct answers by eyeballing instead of by doing calculations:

Choice A: In the second graph, the percentage revenue from computers in 2004 is about equal to the percentage revenue from computers in 2003. From the first graph, you know the total revenue in 2004 was greater than in 2003. Thus the revenue from computers in 2004 is an equal slice of a larger whole (relative to 2003). → Keep Choice A.
Choice B: In the second graph, the percentage revenue from computers in 2005 is slightly less than the percentage revenue from computers in 2004. From the first graph, you know the total revenue in 2005 was less than in 2004. Thus the revenue from computers in 2005 is a smaller slice of a smaller whole (relative to 2004). → Eliminate Choice B.
Choice C: In the second graph, the percentage revenue from computers in 2006 is greater than the percentage revenue from computers in 2005. From the first graph, you know the total revenue in 2006 was greater than in 2005. Thus the revenue from computers in 2006 is a larger slice of a larger whole (relative to 2005). → Keep Choice C.
Choice D: In the second graph, the percentage revenue from computers in 2008 is roughly equal to the percentage revenue from computers in 2007. From the first graph, you know the total revenue in 2008 was less than in 2007. Thus the revenue from computers in 2008 is an equal slice of a smaller whole (relative to 2007). → Eliminate Choice D.
Choice E: In the second chart, the percentage revenue from computers in 2010 is roughly equal to the percentage revenue from computers in 2009. In the first chart, you know the total revenue in 2010 was less than in 2009. Thus the revenue from computers in 2010 is an equal slice of a smaller whole (relative to 2009). Eliminate Choice E. The correct answer for Question 2, therefore, is choices A and C.

- Principle 4: Link to what you know. Since these questions test mathematical skills covered in previous guides, you should recall the relevant properties that a question is addressing.

For example, Question 3 requires you to use the average formula twice. Since the total revenues for 2006 and 2007 are roughly equal ($78 million), and the percentage revenues from phones during those two years are roughly equal (30%), the total for those two years is approximately $78 million × 30% × 2 = $46.8 million.

The other data point is the revenue from phones in 2008. The percentage revenue from phones in 2008 is roughly 32%, and the total revenue is roughly $63 million.

Thus the revenue from phones in 2008 is approximately $63 million × 32% = $20.16 million.

The total average is approximately = $22,320,000.

Rounding off to the nearest $100,000 gives an answer of $22,300,000.