Page 174 - Algebra 1

L E S S O N Identifying Misleading Representations
27
of Data
Warm Up
1. Vocabulary A bar graph uses to represent data. (22)
2. True or False: A circle graph shows how data change. (22)
3. Draw a graph that represents a flag being raised up a flagpole slowly at the
(Inv 2)
beginning and quickly at the end. 4. Solve 2(2x + 3) = 24.
(26)
New Concepts When displaying data, components such as the scale or labels can make a graph misleading.
Example
1
Identifying Misleading Line Graphs
The line graph shows the number of members of a health club each month since it opened. Explain why the graph may be misleading.
Number of Members at Renaldo’s Health Club
900
800
700
600
SOLUTION Because the scale does not start at zero, the membership appears to have increased much more than it actually did.
Another characteristic that may create a misleading graph is the size of the increments in the scale.
Identifying Misleading Bar Graphs
A radio station conducted a survey of music preferences of listeners. The bar graph shows the results. Explain why the graph may be misleading.
Hint
When there is a large
gap between data values, a graph may use a broken axis. In the graph showing memberships, the vertical axis has a broken scale.
Example
2
SOLUTION
Listener Music Preferences
1500
1000
500
0
Rock Pop Hip-Hop Other
Online Connection www.SaxonMathResources.com
The large increments of the scale make the data values appear to be closer than they actually are.
Lesson 27 159
Number of Listeners
Number of Members
Jan Feb Mar Apr May Jun