The Bank Manager believes that customer satisfaction may be directly related to how long it takes a Bank Teller to complete a customer transaction. The Bank Manager also believes that customer satisfaction may be related to how long a person remains a customer of the bank before the customer transfers his or her account to another bank. Therefore, because of customer satisfaction, the time the customer has to wait for a Bank Teller to process his or her transaction may be indirectly related to the number of customers that the bank has at any moment in time.
The Bank Manager reviewed the bank’s records and determined that customers remained with the bank for an average of 7.4 years with a standard deviation of 0.8 years.
Part One: The Bank Manager would like to know how many customers are still with the bank after 9 years. Use reliability theory to answer this question.
t = x = 9 years
Mean Life = u = 7.4 years
Standard Deviation = sigma = 0.8 years
Z = (x - u) / sigma
Z =
From the Normal Table, or Table N:
P(t) =
Part Two: In your own words clearly explain to the Bank Manager what the above numbers indicate.