Q1) In Dallas, some fire trucks were painted yellow (in spite of red) to heighten their visibility. In a test period, fleet of red fire trucks made 153,348 runs and had 20 accidents, whereas the fleet of yellow fire trucks made 135,035 runs and had four accidents. At α = .01, did yellow fire trucks have a considerably lower accident rate?
a) Mention the hypotheses.
b) State the decision rule and sketch it.
c) Determine the sample proportions and z test statistic.
d) Make a decision.
e) Determine the p-value and interpret it.
f) If statistically significant, do you believe the difference is large enough to be significant? If so, to whom, and explain why?
g) Is normality assumption fulfilled? Describe.
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Accident rate for dallas fire trucks
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statistic
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red fire trucks
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yellow fire trucks
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number of accidents
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x1=20 accidents
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x2=4 accidents
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number of fire runs
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n1=153,348 runs
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n2=135,035 runs
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