502 CHAPTER 9 Inferences from Two Samples 5. CD Sales Listed below are amounts of CD sales in billions of dollars (based on data from the Recording Industry Association of America). The amounts are listed in order by year beginning with the year 1999. 12.8 13.2 12.9 12.0 11.2 11.4 10.5 9.4 7.5 5.5 4.3 3.4 3.1 2.3 2.1 1.8 1.4 1.1 1.1 0.9 6.Eyewitness Accuracy of Police An experiment tested eyewitness memory of police one week after a non-stressful interrogation of a cooperative suspect and one week after a stressful interrogation of an uncooperative and belligerent suspect. The numbers of details recalled one week after the incident were recorded, and the summary statistics are given below (based on data from “Eyewitness Memory of Police Trainees for Realistic Role Plays,” by Yuille et al., Journal of Applied Psychology, Vol. 79, No. 6). Higher values for x represent better memory recall. Non-stressful interrogation: n = 40, x = 53.3, s = 11.6 Stressful interrogation: n = 40, x = 45.4, s = 13.2 7.Deaths from Risk Factors Here are estimated numbers of global deaths for common risk factors in a recent year: alcohol (2.3 million), drug use (0.5 million), total pollution (9.2 million), road accidents (1.4 million), tobacco smoking (7.2 million), malnutrition (1.4 million), war and murder (0.4 million). 8.Heights of Supermodels Adult women from the general population have a mean height of 162 cm. Listed below are the heights (cm) for the simple random sample of female supermodels Lima, Bundchen, Ambrosio, Ebanks, Iman, Rubik, Kurkova, Kerr, Kroes, Swanepoel, Prinsloo, Hosk, Kloss, Robinson, Heatherton, and Refaeli. 178 177 176 174 175 178 175 178 178 177 180 176 180 178 180 176 9. Daily 4 Lottery Numbers The table below summarizes results from 250 drawings for the California Daily 4 lottery game. Number Selected 0 1 2 3 4 5 6 7 8 9 Frequency 101 90 115 105 92 102 82 114 86 113 10. Manatees Listed below are numbers of registered pleasure boats in Florida (tens of thousands) and the numbers of manatee fatalities from encounters with boats in Florida for each of several recent years. Pleasure Boats 99 99 97 95 90 90 87 90 90 Manatee Fatalities 92 73 90 97 83 88 81 73 68 Queues Listed on the next page are ten pairs of waiting line times (sec) from Data Set 30 “Queues” in Appendix B. The first row lists actual wait times of drivers in two lines at a Delaware vehicle inspection station, and the second row lists modeled times for the same drivers assuming that they used a single common waiting line for the same two inspection stations. a. Do the differences appear to satisfy the requirement of being from a normally distributed population or n 7 30? b. Use a 95% confidence level and use the methods of this chapter to construct a confidence interval for testing the claim that there is no difference in wait times between the two-line configuration and the single-line configuration. Technology Project
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