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

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) (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
RELATED QUESTIONS
The population mean waiting time of customers of the XYZ Burger chain is 3.4 minutes with (answered by stanbon)

when a customer enters a pharmacy the probability that he or she will have 0, 1, 2, 3... (answered by stanbon)

2. The Mac Burger restaurant chain claims that the waiting time of customers for... (answered by Boreal)

The waiting time until a customer is served at a fast food restaurant during lunch hours... (answered by Boreal)

At the end of the day, a pharmacist counted and found she has 4/3 as many prescriptions... (answered by jorel555)

At the end of the day, a pharmacist counted and found she has 4/3 as many prescriptions... (answered by ikleyn,greenestamps)

Question A. A survey on the Cypriot market on the mean amount spent per customer for... (answered by Boreal)

Jim’s Auto Insurance Company customers sometimes have to wait a long time to speak to a (answered by math_tutor2020)

a Bank has 2 tellers. customers arriving at the bank vary between 1 and 6 per minute.... (answered by stanbon)