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What is a Circle/Pie Graph and When are they Used?

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What is a Circle Graph or Circle Pie Chart
Favorite Colors

Favorite Colors

D. Russell
Numerical information and data can be displayed in a variety of ways that include but are not limited to charts, tables, plots and graphs. Sets of data are easily read or understood when they are displayed in a user friendly format. In a circle graph (or pie chart), each part of the data is represented by a sector of the circle. Prior to technology and spreadsheet programs, one would require skill with percentages and with drawing angles. However, more often than not, the data is put into columns and converted into a circle graph or pie chart using a spreadsheet program or graphing calculator. In a pie chart or circle graph, the size of each sector will be proportional with the actual value of the data it represents as seen in the images. Percentages of the total of the sample are usually what is represented in the sectors. One of the more common uses for circle graphs or pie charts are poll results and surveys.

In the favorite color graph, 32 students were given the oppportunity to choose from red, blue, green, orange or other. If you knew that the following answers were 12, 8, 5, 4 and 3. You should be able to select the largest sector and know that it represents the 12 students who selected red. When you calculate the percentage, you will soon discover that of the 32 students surveyed, 37.5% selected red. You have enough information to determine the percentage of the remaining colors.

The pie chart tells you at a glance without having to read the data which would look like:
Red 12 37.5%
Blue 8 25.0%
Green 4 12.5%
Orange 5 15.6%
Other 3 9.4%

On the next page is the results of a vehicle survey, the data is given and you need to determine which vehicle corresponds to the color on the pie chart/circle graph.

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