Quiz 5: Hypothesis Testing in Statistics - Fuser Lifetime and Fertilizer Comparison, Quizzes of Probability and Statistics

Download Quiz 5: Hypothesis Testing in Statistics - Fuser Lifetime and Fertilizer Comparison and more Quizzes Probability and Statistics in PDF only on Docsity! Quiz 5 Name Math 243 GTF May 7, 2009 Disc. Time (1) Paul leases high volume photocopiers, with the agreement to fix each copier when it breaks. To evaluate his current parts provider, he decides to test its claim for the life expectancy of a part called the “fuser” by checking it against his data for that part. (Assume the ap- propriate test is safe to use.) He figures that if the provider has given accurate information about it’s fusers, then he can trust its accuracy in other areas as well. He installs 14 fusers in 2006 and waits until his technicians have brought them all back broken. He records the following lifetimes (in thousands of pages printed) for the fusers: 195.80 227.50 140.70 173.30 215.90 243.50 193.80 205.30 251.60 180.10 231.70 172.40 187.90 246.50 The provider claims a mean life expectancy of 190 thousand pages with a standard devi- ation of 28 thousand pages. Paul wants to be sure of a decision (to not trust his current provider) at the α = 0.02 level. What does he decide? Answer using the following steps (then answer the following questions). (a) State the null and alternative hypotheses. (b) Calculate the test statistic. Show your work. (c) Give a P -value (or give two values between which P lies). (d) Draw the appropriate conclusion, expressing it in words appropriate for the context of the problem. Be sure to mention the results of the previous steps when stating the reasons. 1