Six hundred adult Americans were asked by telephone poll, "What do you think constitutes a middle-class income?" Also, include the left endpoint but not the right endpoint. Salary ($)Relative Frequency
< 20,000.02
20,000–25,000.09
25,000–30,000.19
30,000–40,000.26
40,000–50,000.18
50,000–75,000.17
75,000–99,999.02
100,000+.01

What percentage of the survey answered "not sure"?
What percentage think that middle class is from $25,000 to $50,000?
Find the 40th and 80th percentiles.
40th percentile = Between $ and $
80th percentile = Between $ and $