Pre-Algebra Chapter 9

A Follow-Up of Lesson 9-3
Circle Graphs and Spreadsheets
In the following example, you will learn how to use a computer spreadsheet
program to graph the results of a probability experiment in a circle graph.
Example
The spinner like the one shown at the right was spun
20 times each for two trials. The data are shown below.
Use a spreadsheet to make a circle graph of the results.
Enter the data in a spreadsheet as shown.
The spreadsheet evaluates
the formula SUM(D3:D14)
to find the total.
Select the data to be included in your graph. Then use the graph tool to
create the graph. The spreadsheet will allow you to add titles, change
colors, and so on.
Exercises
1. Describe the results you would theoretically expect for one trial of 20 spins.
Explain your reasoning.
2. Make a spinner like the one shown above. Collect data for five trials of 20 spins
each. Use a spreadsheet program to create a circle graph of the data.
3. A central angle is an angle whose vertex is the center of a circle and whose sides
intersect the circle. After 100 spins, what kind of central angle would you
theoretically expect for each section of the circle graph? Explain.
4. Predict how many trials of the experiment are required to match the theoretical
results. Test your prediction.
5. When the theoretical results match the experimental results, what is true about
the circle graph and the spinner?
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