Bar and Circle Graphs

Sometimes you can draw different graphs to represent the same data, depending on the information you want to share. A bar graph is useful for comparing amounts; a circle graph is useful for comparing percents.

Example

Display the 2007 data on immigration to the United States in a bar graph and a circle graph.

To make a circle graph, first find the percent of the data in each category. Then express each percent as a decimal and multiply by 360 ° 360 degrees to find the size of each central angle.

Draw a circle and use a protractor to draw each central angle.

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SOURCE: Department of Homeland Security

To make a bar graph, place the categories along the bottom axis. Decide on a scale for the side axis. An appropriate scale would be 0–300, marked in intervals of 50. For each data item, draw a bar whose height is equal to the data value.

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Exercises

Display the data from each table in a bar graph and a circle graph.

1. NASA Space Shuttle Expenses, 2000

   Operation	Millions of Dollars
   Orbiter, integration	698.8
   Propulsion	1,053.1
   Mission, launch operations	738.8
   Flight operations	244.6
   Ground operations	510.3

   SOURCE: U.S. National Aeronautics and Space Administration

2. Cable TV Revenue, 2006

   	Millions of Dollars
   Airtime	4,566
   Basic service	42,918
   Pay-per-view, premium services	13,322
   Installation	729
   Other	27,188

   SOURCE: U.S. Census Bureau

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