1. General Hospital's patient account division has compiled data on the age of accounts receivable. The data collected indicate that the age of the accounts follows a normal distribution with = 28 days and a = 8 days. What portion of the accounts are between 20 and 40 days old-that is, P(20 x 40)?

The hospital administrator is interested in sending reminder letters to the oldest 1c7c of accounts. How many days old should an account be before a reminder letter is sent?

The hospital administrator wants to give a discount to those accounts that pay their balance by the 21st day. What percentage of the accounts will receive the discount?

2. The Webster National Bank is reviewing its service charges and interest-paying policies on checking accounts. The average daily balance on personal checking accounts is $550, with a standard deviation of $150. In addition, the average daily balances are normally distributed.

a. What percentage of personal checking account customers carry average daily balances in excess of 5800?
b. What percentage carry average daily balances below $200?
c. What percentage carry average daily balances between $300 and $700?
d. The bank is considering paying interest to customers carrying average daily balancesmin excess of a certain amount. If the bank does not want to pay interest to more than 5% of its customers, what is the minimum average daily balance it should be willing to pay interest on?