Reading Percent Data from Graphs

Learning Outcomes

  • Read and interpret data from pie charts as percents

Pie Charts

Circle graphs, or pie charts, represent data as sections of the circle (or “pieces of the pie”), corresponding to their percentage of the whole. Circle graphs are often used to show how a whole set of data is broken down into individual components.

Here’s an example. At the beginning of a semester, a teacher talks about how she will determine student grades. She says, “Half your grade will be based on the final exam and  [latex]20\%[/latex] will be determined by quizzes. A class project will also be worth [latex]20\%[/latex] and class participation will count for [latex]10\%[/latex].” In addition to telling the class this information, she could also create a circle graph.

Pie chart for grade determination. Final exams determine 50 percent, Quizzes 20 percent, Class Projects 20 percent, and Class Participation 10 percent.

This graph is useful because it relates each part—the final exam, the quizzes, the class project, and the class participation—to the whole.


If the total number of points possible in the class is  [latex]500[/latex], how many points is the final exam worth?

Try It

In the following video, an example of using a pie chart to determine a percent of a whole is shown.


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