10-22 (3rd edition) Two suppliers manufacture a plastic gear used in a laser printer. The impact strength of these gears measured in foot-pounds is an important characteristic. A random sample of 10 gears from supplier 1 results in xbar1=290 and sig1=12, while another random sample of 16 gears from the second supplier results in xbar2=321 and sig2=22. (a) Is there evidence to support the claim that supplier 2 provides gears with higher mean impact strength? Use alpha=0.05 and assume that the variances are not equal. (b) What is the p-value for this test? (c) Do the data support the claim that the mean impact strength of gears from supplier 2 is at least 25 foot-pounds higher than that of supplier 1? Make the same assumptions as in part (a).

What is the sample claim H1 in (a)? What is H0?[br]What is the sample claim H1 in (c)? What is H0?[br]Using alpha=0.05, for what amount of foot-pounds could we claim that the mean impact strength of gears from supplier 2 is higher?[br]What changes using alpha=0.025?[br][br]Source: Source of materials: Applied statistics and probability for engineers, 3rd ed., Chapter 10, D. Montgomery, G.Runger, 2010, 978-0470053041, Wiley & Sons.