Unit 2A

4a. The population is the 3500 students at your college. The sample is the 35 students in your mathematics class. The population parameter is the average amount of sleep for the population.

4b. The raw data consist of the average amount of sleep for each of the 35 students.

4c. The sample statistic is the average sleep for the 35 students, in this case 7.3 hours.

4d. Your estimate of the population parameter should be 7.3 hours of sleep. Because the students of your mathematics class may not be representative of the entire student body and because the sample size is not large, this estimate my not be reliable.

12. This is a study about tuna fish, not about people! The population is all tuna fish consumed by U.S. residents. The sample could consist of randomly selected tuna fish at randomly selected fish processing plants (around the world) that provide fish to the United States. It could also consist of randomly selected tuna fish (fresh and canned) at randomly selected stores across the country.

24. This study is observational. However, the sample most likely fell naturally into two groups: those who exercised regularly and those who did not. So effectively there was a case-control group.

26. There are two ways to approach this question. You could conduct an experiment in which one group listens to jazz regularly while studying and one control group listens to other music or no music. I don’t know of a way to prevent a person from knowing what kind of music s/he is hearing, so the experiment cannot be single-blind or double-blind. Similarly, there can be no placebo in this experiment. However, you might argue that making people listen to music that they may not like will certainly not improve studying and grade. If this is the case, then a case-control observational study would be better.

Unit 2B

2. There is little reason to suspect that people whose last names begins with A are unrepresentative, so this process is relatively free of bias. Including people without phones or who are not listed in the directory would be preferable.

Unit 2C

4a. The population in the 30-34 age group is approximately 22 million.

4b. The population in the 65-70 age group is approximately 10 million.

4c. The most populous age group is 35-40.

4d. The bulge is the so-called baby boomers.

4e. An estimate of the total population could be found by adding up the heights of all the bars in the graph.

18. Here is one possible graph for the data.