After completing this unit, you should be able to:
Circle graphs, also called pie charts, are a type of graph used to represent a part to whole relationship. Properties of Circle Graphs:
In this unit we will review how to read a circle graph. An example of a circle graph is given below.
When reading this circle graph we look for the following pieces
of information: the graph title, individual sectors and their
relative sizes, and the sector labels (one for each sector). Let's
take a closer look at each of these.
Graph TitleA graph title gives an overview of the information displayed in the graph. The title is given at the top of the graph. SectorsEach sector represents one part of the whole. The size of each sector represents its fraction of the whole. Sector LabelsThe label of each sector indicates the category of information it refers to, and may also give numeric data (often a percentage) so we know the size of each sector. 

Let's use the circle graph given here as an example of how
to get information from a circle graph. Looking at the elements
of this graph we find:
We would expect the graph associated with this title to contain the names of different sources of revenue for the federal government, with some information on the relative amounts from each revenue source.
The graph below contains four different sectors. This means the graph displays four different sources of revenue. The largest sector is a little less than half of the whole circle. There is another source that is also relatively large, and then there are two smaller sources of revenue. 
The graph has a label for each sector. Each label shows what type of revenue it corresponds to, and the percentage of the whole for that sector. From the graph we can see:

We determine this by finding the ratio of Individual Income Tax to Corporate Income Tax. From the circle graph we know this is 45:10, which is 4.5:1. (If you have any problem understanding ratios you should review the units on ratios and proportions.)
When we are presented with a circle graph, we want to be able to make statements about the sectors of the graph, relative to one another, and relative to the entire circle. From this one example, we can see the amount of information we can get, and all from looking at one circle graph! Now, let's try an example of reading a circle graph and answering specific questions about the data presented.
Based on the circle graph given below, answer the following questions.

Expenditures for State
and

Below are the answers to the example above. To view
the detailed soluntion to a specific
question, click on that question, or you may also what the vew
the solution from the beginning by clicking the link: [view detailed discussion of the solution]
Now try the practice for this unit. When you feel you are ready, move on to the next unit on construction circle graphs.







