10.11: Circle Graphs to Display Data
Have you ever looked at statistics in a magazine or online?
Jillian loves quilting. At first, she thought that she would love it because it is something that she could do with her grandmother, but now she is sure that she actually really loves the quilting itself. Jillian loves creating something with her hands and seeing the finished project.
Jillian asked her grandmother how long she had been quilting and her grandmother told her that she had been quilting for a long time, long before Jillian was even born. Jillian began to wonder how many other people in the world quilt.
During a trip to the library, Jillian used the computer to do some research. She found that the number of people quilting in the United States has increased significantly from 2006 to 2009. Quilters.com completed a survey and here are their results.
In 2006, 21.3 million people were quilting. That means that about 13% of all Americans were making quilts.
In 2009, 27 million people were quilting. That means that about 17% of all Americans were quilting.
That is an increase of 4% in just three years! It might not seem like much, but it is a significant increase!
Jillian wants to show her grandmother the results of the survey. She has decided to create a picture of the data to show how the information has changed. To do this, she is going to create a circle graph.
She will create two circle graphs, one for 2006 and one for 2009.
Do you know how to do this? During this Concept you will continue learning about circles. At the end of the Concept, you will see how Jillian used a circle to display the quilting data.
Guidance
In our opening problem, Jillian wants to display her quilting data in a circle graph. We can use circle graphs to display realworld data. In fact, we do it all the time.
What is a circle graph?
A circle graph is a visual way to display data using circles and parts of a circle.
A circle graph uses a circle to indicate 100%. The entire circle represents 100% and each section of a circle represents some part out of 100.
You can see here that this circle graph is divided into five sections. Each section represents a part of a whole.
Back in an earlier Concept, we looked at the spending habits of a teenager. Here you can see that 50% of his money went into savings. 40% of his money was spent on food and that 10% of his money went to baseball cards.
Use this circle graph to answer the following questions.
Example A
What is the most popular music selection?
Solution: Pop music
Example B
What percent of the students chose pop music?
Solution: 50%
Example C
What percent of the students chose rock music?
Solution: 25%
When Jillian creates her circle graphs, she will be able to create ones that show how quilting has grown from 2006 to 2009. Let’s go and revisit that introductory problem now.
Here is the original problem once again. Reread it and underline any important information.
Jillian loves quilting. At first, she thought that she would love it because it is something that she could do with her grandmother, but now she is sure that she actually really loves the quilting itself. Jillian loves creating something with her hands and seeing the finished project.
Jillian asked her grandmother how long she had been quilting and her grandmother told her that she had been quilting for a long time, long before Jillian was even born. Jillian began to wonder how many other people in the world quilt.
During a trip to the library, Jillian used the computer to do some research. She found that the number of people quilting in the United States has increased significantly from 2006 to 2009. Quilters.com completed a survey and here are their results.
In 2006, 21.3 million people were quilting. That means that about 13% of all Americans were making quilts.
In 2009, 27 million people were quilting. That means that about 17% of all Americans were quilting.
That is an increase of 4% in just three years! It might not seem like much, but it is a significant increase!
Jillian wants to show her grandmother the results of the survey. She has decided to create a picture of the data to show how the information has changed. To do this, she is going to create a circle graph.
She will create two circle graphs, one for 2006 and one for 2009.
Let’s look at Jillian’s data.
The first circle graph will show that 13% out of 100% of people were quilting in 2006. Here is the circle graph.
The second circle graph shows that in 2009, the number of people quilting increased to 17% out of 100%.
Now Jillian has two circle graphs that she can share with her grandmother.
Vocabulary
Here are the vocabulary words in this Concept.
 Area
 the surface or space of the figure inside the perimeter.
 Radius
 the measure of the distance halfway across a circle.
 Diameter
 the measure of the distance across a circle
 Squaring

uses the exponent 2 to show that a number is being multiplied by itself.
32=3×3
 Pi
 the ratio of the diameter to the circumference. The numerical value of pi is 3.14.
Guided Practice
Here is one for you to try on your own.
What percent of the students enjoy country music?
Answer
To figure this out, we have to look at the whole of the circle and remember that it is equal to 100%. 25% of the circle has only been partially filled in.
10% or
Then there is an unknown percent of the students that enjoy country music.
To figure this out we can subtract the percent of students who enjoy Jazz music from the open 25%.
Video Review
Here is a video for review.
Khan Academy: Reading Pie Graphs (Circle Graphs)
Practice
Directions: Use the survey to answer each question.
A survey of 300 people asked them to name their favorite spectator sport. The results are shown in the circle graph below.
1. What was the most favorite spectator sport of the people surveyed?
2. What was the least favorite spectator sport of the people surveyed?
3. What percent of the people surveyed said that football was their favorite spectator sport?
4. How many people said that basketball was their favorite spectator sport?
5. How many more people said that soccer was their favorite sport than ice hockey?
6. What percent of the people chose baseball and soccer as their favorite sports?
7. What percent of the people did not choose baseball?
8. What percent of the people did not choose hockey?
9. What percent of the people chose tennis or soccer as their favorite sports?
10. What percent of the people did not choose basketball or tennis?
11. What percent of the people did choose tennis as a favorite sport?
12. What percent of the people did not choose football?
The table shows the how much money the students in the seventh grade have raised so far for a class trip. Make a circle graph that shows the data.
Fundraiser  Amount 

Car wash  $150 
Book sale  $175 
Bake sale  $100 
Plant sale  $75 
13. Make a list of 5 popular ice cream flavors. Then survey your classmates asking them which of the 5 flavors is their favorite ice cream flavor. Use the data to make a circle graph.
14. Use a newspaper to locate a circle graph of some data. Then write five questions about the data.
15. Now create your own circle graph. Share it with a partner.
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Area
Area is the space within the perimeter of a twodimensional figure.Diameter
Diameter is the measure of the distance across the center of a circle. The diameter is equal to twice the measure of the radius.Pi
(Pi) is the ratio of the circumference of a circle to its diameter. It is an irrational number that is approximately equal to 3.14.Radius
The radius of a circle is the distance from the center of the circle to the edge of the circle.Squaring
Squaring a number is multiplying the number by itself. The exponent 2 is used to show squaring.Image Attributions
Here you'll learn to display data using circle graphs.