Answer:
6.3%
Explanation:
Calculation for what yield (in percentage points) must municipals offer
Using this formula
Yield=Corporate bonds yield×(1-Tax rate)
Let plug in the formula
Yield=0.09 x (1 - 0.30)
Yield= 0.063 ×100
Yield=6.3%
Therefore the yield that municipals must offer for the investor to prefer them to corporate bonds is 6.3%