SOLUTION: 2. The Mac Burger restaurant chain claims that the waiting time of customers for service is normally distributed, with the mean of 10 minutes. The quality-assurance department

Question 1119045:
2. The Mac Burger restaurant chain claims that the waiting time of customers for service is normally distributed, with the mean of 10 minutes. The quality-assurance department found in a sample of 25 customers at the warren road Mac burger that the mean waiting time was 8 minute with standard deviation of 2 minutes. At the .05 significance level; can we conclude that the mean waiting time is less than 10 minutes?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
Ho--same time
Ha--different time
test stat is a t 0.975,df=24
critical value |t|>2.064
t=(x bar-mean)/s/sqrt(n)=(8-10)/2/sqrt(25)= -2*5/2=-5. This is highly significant, and the waiting time is concluded to be not 10 minutes (given null and alternative hypotheses). One may conclude that it is fewer than 10 minutes. One could use a one-way test in this instance if one knew for sure it would be less, and then the critical value is less as well.
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