back to Unit 12

Constructing Circle Graphs

When data are expressed as parts of a whole, you can display the data in a circle graph.  The entire circle represents 100% of the data.  The different parts are represented as sectors of the circle.  since there are 360º in a circle, the sum of the central angles formed by the sectors must be 360º

Example:  Draw a circle graph to represent the following data.  In a survey, 350 people named their favorite movie:

Star Wars,  119

Indiana Jones and the Temple of Doom,  98

Gone with the Wind, 77

White Christmas,  56

Step 1: Find the decimal for each part of the whole. The whole in this case is 350 (all the people surveyed)

Star Wars:                                                Gone with the Wind:

Indiana Jones:                                      White Christmas:

Step 2: Find the measure of each films central angle (What part of the circle they should be drawn)

 Star Wars:  .34 · 360 = 122.4º  round to 122º Indiana Jones: .28 ·  360 = 100.8º  round to 101º Gone With the Wind: .22 ·  360 = 79.2º  round to 79º White Christmas: .16 ·  360 = 58º  round to 58º