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 (the personal checking account) customers carry average daily balances more than $800 for which the bank is willing to pay interest on? b. What percentage carries average daily balances below $200? c. What percentage carries average daily balances between $300 and $700?