http://www.ck12.org Chapter 7. Organizing and Displaying Data
The above pie chart was created by using a protractor and graphing each section of the circle according to the
number of degrees needed. From the graph, you can see that more donations were of Type O than any other type.
The fewest number of donations of blood collected was of Type AB. Notice that the percentages have been entered
in each section of the graph and not the numbers of degrees. This is because degrees would not be meaningful to an
observer trying to interpret the graph. In order to create a pie chart by using a circle, it is necessary to use the formula
to calculate the number of degrees for each section, and in order to create a pie chart by using a hundreds disk, it is
necessary to use the formula to determine the percentage for each section. In the end, however, both methods result
in identical graphs.
Example C
A new restaurant is opening in town, and the owner is trying very hard to complete the menu. He wants to include
a choice of 5 salads and has presented his partner with the following pie chart to represent the results of a recent
survey that he conducted of the town’s people. The survey asked the question, "What is your favorite kind of salad?"
Use the pie chart to answer the following questions:
- Which salad was the most popular choice?
- Which salad was the least popular choice?
- If 300 people were surveyed, how many people chose each type of salad?
- What is the difference between the number of people who chose the spinach salad and the number of people
who chose the garden salad? - The most popular salad was the caesar salad.
- The least popular salad was the taco salad.
- Caesar salad: 35%= 10035 = 0. 35
( 300 )( 0. 35 ) =105 people