The National Association of Real Estate Sellers has collected these data on a sample of 130 salespeople representing their total commission earnings annually:
| Earnings | Frequency |
| $ 5,000 or less | 5 |
| $ 5,001–$10,000 | 9 |
| $10,001–$15,000 | 11 |
| $15,001–$20,000 | 33 |
| $20,001–$30,000 | 37 |
| $30,001–$40,000 | 19 |
| $40,001–$50,000 | 9 |
| Over $50,000 | 7 |
Construct an ogive that will help you answer these questions.
- (a) About what proportion of the salespeople earns more than $25,000?
- About what does the “middle” salesperson in the sample earn?
- Approximately how much could a real estate salesperson whose performance was about 25 percent from the top expect to earn annually?
Springfi eld is a college town with the usual parking problems. The city allows people who have received tickets for illegally parked cars to come in and make their case to an administrative offi cer and have the ticket voided. The town’s administrative offi cer collected the following frequency distribution for the time spent on each appeal:
The Nebraska Department of Agriculture has these data representing weekly growth (in inches) on samples of newly planted spring corn:
The National Safety Council randomly sampled the tread depth of 60 right front tires on passenger vehicles stopped at a rest area on an interstate highway. From its data, it constructed the following frequency distribution:
The High Point Fastener Company produces 15 basic items. The company keeps records on the number of each item produced per month in order to examine the relative production levels. Records show the following numbers of each item were produced by the company for the last month of 20 operating days:
The administrator of a hospital has ordered a study of the amount of time a patient must wait before being treated by emergency room personnel. The following data were collected during a typical day:
In the population under study, there are 2,000 women and 8,000 men. If we are to select a sample of 250 individuals from this population, how many should be women to make our sample considered strictly representative?
The U.S. Department of Labor publishes several classifi cations of the unemployment rate, as well as the rate itself. Recently, the unemployment rate was 6.8 percent. The department reported the following educational categories:
A sports psychologist studying the effect of jogging on college students’ grades collected data from a group of college joggers. Along with some other variables, he recorded the average number of miles run per day. He compiled his results into the following distribution:
A behavioral researcher studying the success of college students in their careers conducts interviews with 100 Ivy League undergraduates, half men and half women, as the basis for the study. Comment on the adequacy of this survey.