Suppose an investor is considering a corporate bond with a 7.17% before-tax yield and a municipal bond with a 5.93% before-tax yield. At what marginal tax rate would the investor be indifferent between investing in the corporate and investing in the muni?

James is an employee in the widget inspection department of xyz systems, a government contractor. james was part of a 3-person inspection team that found a particular batch of widgets did not meet the exacting requirements of the u.s. government. in order to meet the tight deadline and avoid penalties under the contract, james' boss demanded that the batch of widgets be sent in fulfillment of the government contract. when james found out, he went to the vice president of the company and reported the situation. james was demoted by his boss, and no longer works on government projects. james has a: