http://www.ck12.org Chapter 7. Organizing and Displaying Data
7.7 Bar Graphs
Here you’ll learn what type of data lends itself to a bar graph and how to interpret bar graphs.
You and your five friends have been saving money for a special trip. Bill has saved $585, Susan has saved $785,
Amanda has saved $623, Julie has saved $95, Roberto has saved $897, and you’ve saved $675. How can you
represent what you’ve saved for your trip on a graph?
Watch This
First watch this video to learn about bar graphs
MEDIA
Click image to the left for more content.CK-12 Foundation: Chapter7BarGraphsA
Then watch this video to see some examples.
MEDIA
Click image to the left for more content.CK-12 Foundation: Chapter7BarGraphsB
Guidance
The different types of graphs that you have seen so far are plots to use with quantitative variables. A qualitative
variable can be plotted using a bar graph. Abar graphis a plot made of bars whose heights (vertical bars) or
lengths (horizontal bars) represent the frequencies of each category. There is 1 bar for each category, with space
between each bar, and the data that is plotted is discrete data. Each category is represented by intervals of the same
width. When constructing a bar graph, the category is usually placed on the horizontal axis, and the frequency is
usually placed on the vertical axis. These values can be reversed if the bar graph has horizontal bars. If bar graphs
are constructed on grid paper, it is very easy to keep the intervals the same size and to keep the bars evenly spaced.
In addition to helping in the appearance of the graph, grid paper also enables you to more accurately determine the
frequency of each class.
Example A
Construct a bar graph to represent the depth of the Great Lakes:
Lake Superior –1,333 ft.