Comparing Costs of Checking Accounts. What would be the net annual cost of the following checking accounts?

a. Monthly fee, $3.75; processing fee, $0.25 per check; checks written, an average of 22 a month.

b. Interest earnings of 6 percent with a $500 minimum balance;

average monthly balance, $600; monthly service charge of $15 for falling below the minimum balance, which occurs three times a year (no interest earned in these months).