Answer:
c. 32.99%
Explanation:
Risk yield = bond yield*(1 - Federal tax rate)
6.50% = 9.70%*(1 - Federal tax rate)
1 - Federal tax rate = 6.50%/9.70%
Federal tax rate = 1 - 6.50%/9.70%
= 32.99%
Therefore, The federal tax rate that you are indifferent between the two bonds is 32.99%