The payroll tax for unemployment insurance in a certain nation taxes all wages up to a maximum per worker of $30,000 at a 5 percent flat rate. What are the marginal average tax rates on the wages for each of the following three workers? a) A restaurant worker with annual wages of $18,000. b) An assistant bank manager with wages of $35,000 per year. c) A corporate CEO with an annual salary of $500,000 per year