Lesson 9-8

Example 1 Identify a Misleading Graph
CARS Which graph could be used to indicate a greater decrease in the price of gasoline? Explain.

	Source: narprail.com

Both graphs show that gas prices have decreased by $1.00. The bar graph looks like a $1.00 decrease, while the picture graph indicates a larger decrease.

Example 2 Identify Different Uses of Statistics
GRADES Maria’s grades on her math tests were 99, 98, 99, 72, 65, and 70 each out of 100 points. Predict which measure – mean, median, mode, or range, Maria would want to use to make her results look best. Explain your reasoning.

Mean	 =  or about 83.8

Median	 =  or 85

Mode		99

Range		99 – 65 or 34

Maria would want to show her parents the average showing the highest score. In this case, she would want to show her parents the mode, 99.

Example 3 Determine Accuracy of Conclusions
SURVEY The graph shows the results of a survey on people’s favorite ice cream. An employee of an ice cream parlor looked at the survey and concluded that chocolate chip is twice as popular as vanilla. Determine if the employee’s statement is accurate. Justify your reasoning.

Favorite Ice Cream Flavor	
	
Flavor	

No, the statement is not accurate. The vertical axis does not begin at 0, so the bar for chocolate chip appears to be twice as long as the bar for vanilla. Actually, 85 people voted for chocolate chip, while 70 people voted for vanilla.