A35 TRY IT YOURSELF ANSWERS Chapter 1 Section 1.1 1. The population consists of the responses of all teens in the United States. The sample consists of the responses of the 1516 teens in the survey. The sample data set consists of the 1228 teens who said mental health is a significant issue for young people in the U.S. and 288 teens who did not. 2. (a) Population parameter, because the total spent on employees’ salaries, $5,150,694, is based on the entire company. (b) Sample statistic, because 47% is based on a subset of the population. 3. (a) The population consists of the responses of all Internet users, and the sample consists of the responses of the 513 respondents in the study. (b) The part of this study that represents the descriptive branch of statistics involves the statement “97% of the respondents said music is important to them, and 83% of the respondents said they actively look for new music.” (c) A possible inference drawn from the study is that a large majority of Internet users find music to be important to them and actively look for new music. Section 1.2 1. The city names are nonnumerical entries, so these are qualitative data. The city populations are numerical entries, so these are quantitative data. 2. (1) Ordinal, because the data can be put in order. (2) Nominal, because no mathematical computations can be made. 3. (1) Interval, because the data can be ordered and meaningful differences can be calculated, but it does not make sense to write a ratio using the temperatures. (2) Ratio, because the data can be ordered, meaningful differences can be calculated, the data can be written as a ratio, and the data set contains an inherent zero. Section 1.3 1. This is an observational study. 2. There is no way to tell why the people quit smoking. They could have quit smoking as a result of either chewing the gum or watching the DVD. The gum and the DVD could be confounding variables. To improve the study, two experiments could be done, one using the gum and the other using the DVD. Or just conduct one experiment using either the gum or the DVD. 3. Sample answer: Assign numbers 1 to 79 to the employees of the company. Use the table of random numbers and obtain 63, 7, 40, 19, and 26. The employees assigned these numbers will make up the sample. 4. (1) The sample was selected by using the students in a randomly chosen class. This is cluster sampling. (2) The sample was selected by numbering each student in the school, randomly choosing a starting number, and selecting students at regular intervals from the starting number. This is systematic sampling. Chapter 2 Section 2.1 1. Class Frequency, f 13–20 9 21–28 16 29–36 18 37–44 7 45–52 4 53–60 1 2. Class Frequency, f Midpoint Relative frequency Cumulative frequency 13–20 9 16.5 0.16 9 21–28 16 24.5 0.29 25 29–36 18 32.5 0.33 43 37–44 7 40.5 0.13 50 45–52 4 48.5 0.07 54 53–60 1 56.5 0.02 55 Σf = 55 Σ f n = 1 Sample answer: The most common range of points scored by winning teams is 29 to 36. About 9% of the winning teams scored more than 45 points. 3. 16.5 24.5 32.5 40.5 48.5 3 6 9 12 15 18 21 Frequency Points scored 56.5 Points Scored by Winning Super Bowl Teams Sample answer: The most common range of points scored by winning teams is 29 to 36. About 9% of the winning teams scored more than 45 points.
RkJQdWJsaXNoZXIy NjM5ODQ=