In the United States, high job turnover rates are common in many industries and are associated with high product defect rates. High turnover rates mean more inexperienced workers who are unfamiliar with the company's product lines (Stevenson, Prodi~ction/Operutions Management, 1996). In a recent study, five Japanese and five U.S. plants that manufacture air conditioners were randomly sampled; their turnover rates are listed in the accompanying table; a MINITAB descriptive statistics printout is provided at the bottom of the page.

U.S. Plants Japanese Plants ..........................................................

7.11% 3.52% 6.06 2.02 8.00 4.91 6.87 3.22 4.77 1.92

a. Do the data provide sufficient evidence to indicate that the mean annual percentage turnover for US. plants exceeds the corresponding mean percentage for Japanese plants'? Test using a = .05.

b. Report and interpret the observed significance level of the test you conducted in part a.

c. List any assumptions you made in conducting the hypothesis test of part

a. Comment on their validity for this application.