Answer:
3.5 percent
Explanation:
Data provided in the question
Invested amount = $15,000
Annual interest rate tax-exempt = 3.5%
Corporate bonds annual interest = 4.75%
So after considering the marginal tax rate of 32%, the after tax yield on the municipal bonds is the same as annual interest rate tax- exempt i.e 3.5%
So all other information should be ignored.