Page 175 - Algebra 1

Identifying Misleading Circle Graphs
Example
3
The circle graph shows the number of some types of sandwiches a deli sells in one day. Explain why the graph may be misleading.
SOLUTION The title does not specify that these were the only sandwiches the deli sold, and it may not represent all categories. The deli may also have served a chicken salad or other type of sandwich, making the graph misleading.
Application: Television Prices
Sandwiches
An electronics store created the graph to show the average selling price of a television each year.
Tuna
48 52
Roast Beef 40
Turkey
Ham 84
Example
4
a. Explain why the graph may be misleading.
SOLUTION The large increments make the data values appear to be closer than they actually are.
Average Television Prices
Math Reasoning
Analyze What increments could be used for the vertical axis of the graph in Example 4a so that the graph is not misleading?
1500
1000
500
0
2000 2001 2002 2003 2004 2005
b. What conclusion might be made
from the graph? Why might the store have created this graph?
SOLUTION The graph seems to show that the prices have not increased much over the past five years. The store may want it to appear as though prices have not increased significantly; when in reality they have actually increased by almost 50 percent.
c. Make a graph of the sales data that is not misleading.
SOLUTION Use a broken axis and smaller increments.
Average Television Prices
1000
900
800
700
600
Lesson Practice
a. The graph at right shows (Ex 1) the number of miles a car traveled each year.
Explain why the graph may be misleading.
15000
14000
13000
12000
11000
10000
0
2000 2001 2002 2003 2004 2005
Miles Driven
2001 2002 2003 2004 2005 2006
160 Saxon Algebra 1
Year
Miles
Dollars Dollars