Discussion:
Q: In Dallas some fire trucks were painted yellow. During the test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents. the fleet of yellow trucks made 135,035 runs and had 4 accidents. At a=.01, did the yellow fire trucks have a significantly lower accident rate?
Zc=2.326
Z=2.961
p-value=.0015
normality not justified
State null and alternative hypothesis.
Select a level of significance.
Identify the test statistics (give formula).
Formulate a decision rule.
Make a decision (compute sample proportions and Z statistic).
Compute p-value and interpret it.
Is the normality assumption fulfilled? Explain.