Problem
An investor, Terry Noirs, is in the 35% tax bracket and has been contemplating investing in corporate bonds. After a recent stay at the Eiffel Payne Hospital, a not-for-profit hospital, he learned that they will be issuing tax-exempt bonds for a major expansion. The taxable corporate bonds of the same risk pay 10% interest. What is the minimum rate Eiffel Payne can set for the bonds for Terry to invest in the tax-free bonds?