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Unformatted text preview: Week 3 EText Assignment 10.30 In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents, while the fleet of yellow fire trucks made 135,035 runs and had 4 accidents. At α = . 01, did the yellow fire trucks have a significantly lower accident rate? (a) State the hypotheses. (b) State the decision rule and sketch it. (c) Find the sample proportions and z test statistic. (d) Make a decision. (e) Find the pvalue and interpret it. (f ) If statistically significant, do you think the difference is large enough to be important? If so, to whom, and why? (g) Is the normality assumption fulfilled? Explain. a) : : 2 1 2 1 ≠ = p p H p p H A p1 = red trucks, p2 = yellow trucks b) Reject the null hypothesis if z > 2.3263 2.3263 > shaded area c) 961 . 2 035 , 135 1 348 , 153 1 ) 10 322 . 8 1 ( 10 322 . 8 035 , 135 4 348 , 153 20 1 1 ) 1 ( 10 322 . 8 035 , 135 348 , 153 4 20 5 5 2 1 2 1 5 2 1 2 1 = + = + = × = + + = + + = x x n n p p p p z n n x x p excel stats = Hypothesis test for two independent proportions p1 p2 p c 0.00013 2.96E05 8.32E05 p (as decimal)...
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This note was uploaded on 12/19/2010 for the course MKT 421 taught by Professor Unknown during the Spring '08 term at University of Phoenix.
 Spring '08
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