Answer:
a. Either one, both have the same after-tax yield
Step-by-step explanation:
we have to calculate the after tax return of the bonds:
after tax return of corporate bonds = bond yield x (1 - tax rate) = 7.5% x (1 - 25%) = 7.5% x 0.75 = 5.625%
since municipal bonds are not included as part of Joe's gross income, their after tax rate is equal to their yield = 5.625%
both bonds yield the same after tax return = 5.625%