368 CHAPTER 7 Estimating Parameters and Determining Sample Sizes b. Based on the result from part (a), is it safe to say that the majority of the population does not feel that the song is too offensive. c. What is wrong with this survey? Based on this survey, what do we really know about the population? 9.Flu Shots CVS Pharmacy sponsored a Harris survey of 2,020 adults, and 66% of them said that they plan to get a flu shot this year. Construct a 95% confidence interval estimate of the percentage of all adults who plan to get a flu shot this year. Is there anything about the survey that is questionable? 10.Tour de France Listed below are the average speeds (km>h) of winners of the Tour de France men’s bicycle race. The speeds are listed in order by year, beginning with the year 2000. a. Construct a 95% confidence interval estimate of the population mean. b. Is a confidence interval the best tool for gaining insight into the data? Investigate the data using another tool that would be more helpful. What do you conclude? 39.56 40.02 39.93 40.94 40.55 41.65 40.78 38.98 40.50 40.31 39.59 39.79 39.88 40.54 40.69 39.64 39.62 41.00 40.21 Chicago Commute Time Data Set 31 “Commute Times” from Appendix B includes 1000 commute times (minutes) in Chicago. Use the 1000 commute times for the following. a. Find the mean and standard deviation. b. Generate a histogram and normal quantile plot. Does it appear that the commute times are from a population having a normal distribution? c. In obtaining a 95% confidence interval estimate of the commute times for the population of Chicago, are the requirements for using the t distribution satisfied? Explain. d. Find the 95% confidence interval estimate of the population mean m by using the t distribution. e. Find the 95% confidence interval estimate of the population mean by using 1000 bootstrap samples. f. Compare the results from parts (d) and (e). Which confidence interval is likely to be better? Given that the confidence intervals from parts (d) and (e) are obtained from dramatically different methods, do the two confidence intervals appear to be very different? Technology Project Refer to Data Set 45 “Births in New York” in Appendix B, which contains records from 465,506 births. a. Use the birth weights (grams) of males to construct a 95% confidence interval estimate of the mean birth weight of all males. b. Use the birth weights (grams) of females to construct a 95% confidence interval estimate of the mean birth weight of all females. c. Compare the results from parts (a) and (b). Big (or Very Large) Data Project
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