A city planner claims that the mean speed of westbound traffic along a road segment during morning peak hours is less than 50 miles per hour. In a random sample of 45 motor vehicles traveling westbound along the road segment during morning peak hours, the mean speed is 51 miles per hour. Assume the population standard deviation is 5 miles per hour. At α = 0.05, is there enough evidence to support the city planner’s claim?
(a) Identify the claim and state H0 and Ha,
(b) Find the critical value(s) and identify the rejection region(s),
(c) Find the standardized test statistic z,
(d) Decide whether to reject or fail to reject the null hypothesis,
(e) Interpret the decision in the context of the original claim. If convenient, use technology.