http://www.ck12.org Chapter 7. Organizing and Displaying Data
7.10 Frequency Polygons
Here you’ll learn how to use histograms and tables to construct frequency polygons.
You’ve measured the heights of all the basketball players on your five favorite basketball teams. You’ve constructed
a graph that shows the information you’ve collected in intervals of 5 inches. You’ve also organized the information
into a graph with intervals of 2 inches. Can you determine the mean height of the basketball players by looking at
your graphs?
Watch This
First watch this video to learn about frequency polygons.
MEDIA
Click image to the left for more content.CK-12 Foundation: Chapter7FrequencyPolygonsA
Then watch this video to see some examples.
MEDIA
Click image to the left for more content.CK-12 Foundation: Chapter7FrequencyPolygonsB
Guidance
Another type of graph that can be drawn to represent the same set of data as a histogram represents is a frequency
polygon. Afrequency polygonis a graph constructed by using lines to join the midpoints of each interval, or bin.
The heights of the points represent the frequencies. A frequency polygon can be created from the histogram or by
calculating the midpoints of the bins from the frequency distribution table. Themidpointof a bin is calculated by
adding the upper and lower boundary values of the bin and dividing the sum by 2.
Example A
The following histogram represents the marks made by 40 students on a math 10 test.
Use the histogram to construct a frequency polygon to represent the data.