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MATH 269 HANDOUT #4 Hypothesis Test of Mean Linear Correlation, Linear Regression Instructor: Hernando Burgos Winter 2010

Hypothesis Test of Mean

1) When the workers for a major automobile manufacturer go on strike, there are repercussions to the rest of the economy and, in particular, the dealers who sell the cars and trucks feel the pinch. Dealers like to maintain a 2-month supply to give their customers adequate selection, but when the manufacturer cannot deliver the vehicles, inventories dwindle. The June 1997 days’ supply of Chevrolet S-10 pickup trucks was 106 vehicles, but shortly after the United Auto Workers strike in Flint, Michigan, the June 1998 days’ supply of these trucks had dropped to a mean of 38 and a standard deviation of 16. Suppose one month after the strike was settled, 150 dealers are sampled and S-10 inventories are taken that yield a mean days’ supply of 41 trucks. Based on this new evidence, complete the hypothesis test of H0: = 38 vs. H1: > 38 at the 0.01 level of significance using the probability-value approach. Source: Newsweek, “Big, Empty Lots”, July 27, 1998. a. Define the parameter. b. State the null and alternative hypotheses. c. Specify the hypothesis test criteria. d. Present the sample evidence. e. Find the probability distribution information. f. Determine the results. 2) According to an article in Good Housekeeping (February 1991) a 128.lb woman who walks for 30 minutes four times a week at a steady, 4 mi./hr pace can lose up to 10 pounds over a span of a year. Suppose 50 women with weights between 125 and 130 lb performed the four walks per week for a year and at the end of the year the average weight loss for the 50 was 9.1 lb. Assuming that the standard deviation, σ, is 5, complete the hypothesis test of Ho: µ = 10.0 vs. Ha: µ 10.0 at the 0.05 level of significance using the p-value approach. 3) According to an article in Health magazine (March 1991) supplementation with potassium reduced the blood pressure...