Question

Best-Fast-Food restaurant wants to promote the business by guaranteeing a maximum
waiting time for its patrons. The mean time for brining the order to the table is known
to be 15 minutes per order, with the standard deviation 2.4 minutes. The promotion
states that if the customer is not received the order within that period, the customer will
receive a 50% descount on the nal bill. The manager wants to limit this discount to
at most 5% of the customers. What should the maximum guaranteed waiting time be?
Assume that the service time has normal distribution.

Answer 1

The first step is to use a standard normal distribution table to find the z-score corresponding to 95% cumulative probability. Can you do that?

Answer 2

I KNOW IT IS 1.96

Answer 3

I do not know what to do after that.

Answer 4

Please use the Standard Normal Distibution Table by clicking on this link
http://www.math.bgu.ac.il/~ngur/Teaching/probability/
and selecting 'normal.pdf'
Then find the value of z that corresponds to .9505. Please post this value of z.

Answer 5

*Distribution

Answer 6

@ujuge321 If you have a problem please let me know.

Answer 7

1.65?

Answer 8

but it should be 1.96 for the Z score because alpha is 0.05

Answer 9

The value of z that corresponds to a cumulative probability is 1.65.
Therefore the value we are finding is (1.65 * standard deviation = 3.96) above the mean.
The maximum guaranteed waiting time = 15 + 3.96 = (you can calculate) minutes