BU/MS 310 APPLIED STATISTICS CHAPTER 11 TEST Name: _____________________ SLO 2.8 Make inferences about the variance of a population. Solve the following. 11.1 1) Last year, the standard deviation of the ages of the students at COM-FSM was 1.8 years. Recently, a sample of 61 students had a standard deviation of 2.1 years. We are interested in testing to see if there has been a significant change in the standard deviation of the ages of the students at COM-FSM. Test at a 95% confidence. Solution: = _______ /2 = _______ 2/2 = _______ 21-/2 = _______ df = ____ (n 1) s 2 (n 1) s 2 2 / 2 (12 / 2) Compute a) Interval: ________ to ________ (rounded to the nearest hundredths) b) What is the test statistic? c) Compute for the p-value of the test. d) What is your conclusion? 2) Business Statistics scores of a sample of BU/MS310 students are shown below. Student Score A 22 B 28 C 20 D 21 E 28 F 23 G 26 At 95% confidence, test to determine whether or not the variance of the Stat scores of the population of BU/MS310 students is significantly more than 8. a) Compute the mean and the variance. b) Formulate the hypotheses c) Compute for the test statistic. d) What is the p-value? e) What is your conclusion? 11.2 3) We are interested in determining whether or not the variances of the starting salaries of accounting majors is significantly different from business management majors. The following information was gathered from two samples. Accounting Management 21 18 $3,600 $3,500 $900 $400 Sample Size Average Monthly Income Sample Variance At 90% confidence, test to determine whether or not the variances are equal. a) State the null and alternative hypotheses to be tested. b) Compute the test statistic. c) Determine the p-value. d) What is your conclusion using the p-value approach? e) Use the critical value approach. What is your conclusion? Show how you arrived at this conclusion. 4) The president of the Bank of Guam believes that the variance of the deposits of suburban customers is more than the variance of city customers. Below you are given the results of samples taken from suburban and city customers. Customers Suburban Customers City Customers s 150 90 n 21 19 a) State the null and alternative hypotheses to be tested. b) Compute the test statistic. c) Determine the p-value. 5) d) At 95% confidence, what do you conclude