schools could require random drug tests of students participating in competitive after-school activities such as athletics. Does drug testing reduce use of illegal drugs? A study compared two similar high schools in Oregon. Wahtonka High School tested athletes at random and Warrenton High School did not. In a confidential survey, 5 of 140 athletes at Wahtonka and 26 of 143 athletes at Warrenton said they were using drugs. Regard these athletes as SRSs from the populations of athlete

Mike Jimenez is president of the teachers’ union for Preston School District. In preparing for upcoming negotiations, he would like to investigate the salary structure of classroom teachers in the district. He believes there are three factors that affect a teacher’s salary: years of experience, a rating of teaching effectiveness given by the principal, and whether the teacher has a master’s degree (0 = No, 1 = Yes). A random sample of 20 teachers resulted in the following data.   Salary ($ Thousands) Years of Experience Principal's Rating Master's Degree 51.1 8 95 0 43.6 5 84 0 39.3 2 100 1 53 15 51 1 48.6 11 53 0 55 14 81 1 52 9 85 0 46.8 7 52 1 58.6 22 68 1 41.7 3 97 1 35.7 1 83 0 40.6 5 71 0 61.8 23 77 1 46.7 17 61 0 48.4 12 83 1 43.6 14 71 0 51.8 8 59 1 40.7 4 93 0 42.8 2 58 1 42.9 8 90 0       d. Develop a correlation matrix and state the correlation for each independent variable as it relates to the dependent variable. (Round all…

Amail-order company has two warehouses, one on the West Coast and the second on the East Coast. The company's policy is to mail all orders placed with it within 72 hours. The company's quality control department checks quite often whether or not this policy is maintained at the two warehouses. A recently taken sample of 407 orders placed with the warehouse on the West Coast showed that 366 of them were mailed within 72 hours. Another sample of 297 orders placed with the warehouse on the East Coast showed that 281 of them were mailed within 72 hours. Let p, be the proportion of all orders placed with the warehouse on the West Coast that are mailed within 72 hours, and p, be the proportion of all orders placed with the warehouse on the East Coast that are mailed within 72 hours. a. Construct a 90% confidence interval for the difference between the proportions of all orders placed at the two warehouses that are mailed within 72 hours. Round your answers to two decimal places. to i b.…

The book Survey Responses: An Evaluation of Their Validity, by E. J. Wentland and K. Smith (Academic Press), includes studies reporting the accuracy of answers to questions from surveys. A study by Locander and others considered the question “Are you a registered voter?” Accuracy of response was confirmed by a check of city voting records. Two methods of survey were used: a face-to-face interview and a telephone interview. A random sample of 93 people were asked the voter registration question face-to-face. Seventy-nine respondents gave accurate answers (as verified by city records). Another random sample of 83 people were asked the same question during a telephone interview. Seventy-four respondents gave accurate answers. Assume that the samples are representative of the general population. (a) Let p1 be the population proportion of all people who answer the voter-registration question accurately during a face-to-face interview. Let p2 be the population proportion of all people who…