Interest on municipal bonds is usually exempt from federal income taxes. The interest rate on these bonds is therefore an after-tax rate of return (ROR). Other types of bonds (e.g., corporate bonds) pay interest that is taxable for federal income tax purposes. Thus, the before-tax ROR on such bonds is typically higher than the ROR on municipal bonds. Develop a spreadsheet that contains the before-tax ROR (on taxable bonds) that are equivalent to after-tax RORs of 4%, 5%, and 6% for income tax rates of 15%, 28%, and 35%.