SOLUTION: A chain of pharmacies has collected data on customer waiting times for filling prescriptions. They've found that 10% of the time customers are waiting longer than 15 minutes. In or

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Question 455595: A chain of pharmacies has collected data on customer waiting times for filling prescriptions. They've found that 10% of the time customers are waiting longer than 15 minutes. In order to improve customer satisfaction, the company has stated a goal fo having no more than 2% of their customers wait longer than 15 minutes. If we assume the distribution is normal and the standard deviation (sigma) is 3 minutes, waht should the mean of the waiting times be equal to?
I tried to calculate based on the z score of .98 cumulative area and the equation z= x-m/o (m being mean and o being std. dev.)Using the empirical rule, I know the answer I am getting can not be correct. Any suggestions?
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
The z score for an alpha of .02 is 2.0537
z=(x-m)/s
(15-m)/3=2.0537
15-m=6.1611
-m=-8.8389
m=8.8389
.
Ed