Six hundred adult Americans were asked by telephone poll, "What do you think constitutes a middle-class income?" The results are in the table. 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?
- Construct a histogram of the data.
- Should all bars have the same width, based on the data? Why or why not?
- How should the < 20,000 and the 100,000+ intervals be handled? Why?
- Find the 40th and 80th percentiles.
- Construct a bar graph of the data.
OpenStax Statistics, 2.3 Measures of the Location of the Data, exercise 35