The data analysis questions on the GRE Quantitative Analysis (i.e. Math) section require skills such as “describe past and present trends, predict future events with some certainty…” (The Official Guide to the GRE). What that means for the test-taker is that questions will contain frequency distributions, bar graphs, circle graphs, histograms, scatterplots, and time plots.
This is an example of a histogram. The Y axis will often have probability or, in this case, frequency. The percentages you see in the picture are frequencies that simply refer to how often the event in the X axis occurred. In this case, we are told that out of a total of 25 families, the children were chosen for something. There were six families who had 3 children and one can see on this histogram that the probability of one of those being chosen is 6/25 or 24%.
(Look at the x value of 3 and follow with your finger to the top where it would match about 24% on the Y axis.) This is the kind of histogram interpretation that would be involved in an actual question.
Other data analysis questions may not involve a chart, but just be represented as a word problem. For example, when given daily temperatures for 5 days in July, one would have to find the mean, median, mode and range. A follow-up question might involve changing the given temperatures and then figuring the new quantities.
5 days in July: 90, 88, 85, 85, 87
Mean = (90+88+85+87)/5 = 87
Median = the number in the middle when put in order= 87
Mode = the most frequent number= 85
Range = the difference between the highest and lowest quantity= 5
If each day was 5 degrees cooler, what would the new mean, median, mode and range be? (82, 82, 80, 5)
Hopefully this quick summary has been helpful.
Best of luck! Tanya Panossian-Lesser