SOLUTION: In the past, it has taken an express mail company an average of 2 days to deliver packages. After hiring a consulting firm, they want to know if delivery has improved. Let µ = aver
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Question 1091477: In the past, it has taken an express mail company an average of 2 days to deliver packages. After hiring a consulting firm, they want to know if delivery has improved. Let µ = average number of days needed to deliver a package after hiring a consulting firm. The company wants to test the following:
A sample of 25 packages yields xbar = 1.6 and s = 1.5. For α = 0.05, what would you conclude? Assume the relevant population follows a normal random variable. Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! Ho=no change
Ha=change
alpha=0.05
test statistic is (given normality and s an unbiased estimator of sigma) a t with df=24
critical value is |t| > 2.064
calculation is t=(1.6-2)/1.5/sqrt(25)=-0.4*5/1.5=-2/1.5=-1.33
Fail to reject Ho; insufficient evidence to conclude that delivery has improved.
