Are you avoiding those overly long and tiring GRE quant questions? Yes, we are talking about DI sets. Data Interpretation questions involve analyzing and interpreting data presented in tables, graphs, or other formats. These questions can be in the form of Multiple-choice or Numeric Entries and in this blog, we are discussing both of them.

## Tips for Answering GRE Data Interpretation Questions

Here are some tips for answering GRE Data Interpretation sets:

1. Quickly scan the data presentation to get an overview of what it’s about, without spending too much time on the details. Focus only on the aspects of the data that are necessary to answer the questions. Pay attention to the axes and scales of graphs, the units of measurement, and any notes that provide context for the data.
2. When analyzing graphical data such as bar graphs or line graphs, use the corresponding scales to estimate or compare quantities by sight or measurement. For example, you can compare the relative sizes of bars or sectors, but be cautious of broken scales or bars that do not start at zero.
3. Only use the data presented, everyday knowledge (such as the number of days in a year), and your mathematical knowledge to answer the questions. Do not rely on specialized information from external sources unless it can be derived from the data presented.

## Data Interpretation Practice Question: Multiple-choice Type

Questions 1 to 3 are based on the following data.

Figure 8

Annual Percent Change in Dollar Amount of Sales at Five Retail Stores from 2006 to 2008

 Store Percent Change From 2006 to 2007 Percent Change From 2007 P 10 10 Q -20 -20 R 5 5 S -7 -7 T 17 17

1. If the dollar amount of sales at Store P was \$800,000 for 2006, what was the dollar amount of sales at that store for 2008?
1.     \$727,200
2.     \$792,000
3.     \$800,000
4.     \$880,000
5.     \$968,000

Explanation

According to Figure 8, if the dollar amount of sales at Store P was \$800,000 for 2006, then it was 10% greater for 2007, which is 110% of that amount, or \$880,000. For 2008 the amount was 90% of \$880,000, which is \$792,000. The correct answer is Choice B, \$792,000.

Note that an increase of 10% for one year and a decrease of 10% for the following year does not result in the same dollar amount as the original dollar amount because the base that is used in computing the percentage is \$800,000 for the first change but \$880,000 for the second change.

1. At Store T, the dollar amount of sales for 2007 was what per cent of the dollar amount of sales for 2008? Give your answer to the nearest 0.1%.

Explanation

If A is the dollar amount of sales at Store T for 2007, then 8% of A, or is the amount

of decrease from 2007 to 2008. Thus A – 0.08A = 0.92A is the dollar amount for 2008. Therefore, the desired per cent can be obtained by dividing A by 0.92A

This equals A/0.92A = 1/0.92 = 1.0869565Expressed as a percent and rounded to the nearest 0.1% this number is 108.7%. Thus the correct answer is 108.7% (or equivalent).

1.   Based on the information given, which of the following statements must be true?

Indicate all such statements.

1. For 2008 the dollar amount of sales at Store R was greater than that at each of the other four stores.
2. The dollar amount of sales at Store S for 2008 was 22% less than that for 2006.
3.  The dollar amount of sales at Store R for 2008 was more than 17% greater than that for 2006.

Explanation

For Choice A, since the only data given in Figure 8 are percent changes from year to year, there is no way to compare the actual dollar amount of sales at the stores for 2008 or for any other year. Even though Store R had the greatest per cent increase from 2006 to 2008, its actual dollar amount of sales for 2008 may have been much smaller than that for any of the other four stores, and therefore Choice A is not necessarily true.

For Choice B, even though the sum of the 2% decreases would suggest a 22% decrease, the bases of the percentages are different. If B is the dollar amount of sales at Store S for 2006, then the dollar amount for 2007 is 93% of B, or 0.93B and the dollar amount for 2008 is given by (0.85)(0.93)B which is 0.7905 B.

Note that this represents a per cent decrease of 100-79.05 = 20.95% which is not equal to 22%, and so Choice B is not true.

For Choice C, if C is the dollar amount of sales at Store R for 2006, then the dollar amount for 2007 is given by 1.05C and the dollar amount for 2008 is given by (1.12)(1.05)C, which is 1.176C. Note that this represents a 17.6% increase, which is greater than 17%, so Choice C must be true.

Therefore, the correct answer consists of only Choice C (The dollar amount of sales at Store R for 2008 was more than 17% greater than that for 2006).

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