Checkers Cab Company is trying to decide which brand of tires to employ for the coming year. Based upon current price and prior experience, they have narrowed their choice to two brands, Beltex as well as roadmaster. A current study examined the durability of these tires by using a machine with the metallic device that wore down the tires. The time it took (in hours) for the tire to blow out was recorded. Because the test for each and every tire took a great deal of time and tire itself was ruined by test, small samples of (15 of each brand) were used. Summary of the data - Sample 1: n2=15 mean=3.33 standard dev=0.68 Sample 2: n2=15 mean=3.98 standard deviation=0.38
A) Construct a 90% confidence interval for the ?1-?2, letting ?1 be the average blowout time for all Beltex tires and ?2 be the average blow out time for all Roadmaster tires.
B) Can we conclude that the average blowout times are in fact not the same? Use a significance level of 0.10.