Exam 10: Estimation and Hypothesis Testing: Two Populations

Use the following to answer questions : A sample of 126 corporate managers and another sample of 168 college professors produced mean job-related stress scores of 7.35 for the managers and 6.86 for the professors.Suppose that the standard deviations of the stress scores are 1.12 for the managers and 1.82 for the professors.The null hypothesis is that the mean stress scores are the same for corporate managers and college professors,while the alternative hypothesis is that the mean stress score for managers is different from the mean stress score for professors. -Do you reject or fail to reject the null hypothesis at the 1% significance level? State your answer as "reject" or "fail to reject",but don't include the quotation marks.

Use the following to answer questions : A sample of 20 from a population produced a mean of 66.0 and a standard deviation of 10.0.A sample of 25 from another population produced a mean of 58.6 and a standard deviation of 13.0.Assume that the two populations are normally distributed and the standard deviations of the two populations are equal. The null hypothesis is that the two population means are equal,while the alternative hypothesis is that the two population means are different.The significance level is 5%. -What is the pooled standard deviation of the two samples,rounded to three decimal places?

Use the following to answer questions : A sample of 76 female workers and another sample of 48 male workers from a state produced mean weekly earnings of $743.50 for the females and $777.63 for the males.Suppose that the standard deviations of the weekly earnings are $80.05 for the females and $88.68 for the males.The null hypothesis is that the mean weekly earnings are the same for females and males,while the alternative hypothesis is that the mean weekly earnings for females is less than the mean weekly earnings for males. -Derive the corresponding 95% confidence interval,rounded to two decimal places,for the difference between the mean weekly earnings for all female and male workers in this state.

Use the following to answer questions : In a survey regarding job satisfaction, 574 in a sample of 934 female job-holders stated that they are satisfied with their jobs, while 500 in a sample of 755 male job-holders stated that they are satisfied with their jobs. The null hypothesis is that the proportions of all female and male job-holders who are satisfied with their jobs are the same. The alternative hypothesis is that the proportion of female job-holders who are satisfied with their jobs is lower than the proportion of male job-holders stated who are satisfied with their jobs. The significance level is 2.5%. -What is the value of the pooled sample proportion,rounded to four decimal places?

Use the following to answer questions : A sample of 16 from a population produced a mean of 86.9 and a standard deviation of 14.3.A sample of 18 from another population produced a mean of 75.4 and a standard deviation of 15.9.Assume that the two populations are normally distributed and the standard deviations of the two populations are equal. The null hypothesis is that the two population means are equal,while the alternative hypothesis is that the mean of the first population is greater than the mean of the second population.The significance level is 1%. -Do you reject or fail to reject the null hypothesis at the 1% significance level? State your answer as "reject" or "fail to reject",but don't include the quotation marks.