I don't remember that.
Actually, the amount is $1000.
Luckily,
that rule is programmed into to the processCheck() method.
By using that method,
the rule is correctly applied,
regardless of your poor memory:
bobsAccount.processCheck( 400 ); // correctly applies the rule jillsAccount.processCheck( 4500 ); // correctly applies the rule
If there is a bug in the application of the rule, there is only one place to look for the problem: in the access method.
Another bank charges 10 cents per check for accounts with a balance of more that $500. Our bank needs to do the same in order to keep its customers. How hard will it be to make that change?