Answer:
Interests received from corporate bonds is taxed as ordinary income = 8.8% x (1 - 37%) = 5.544% after tax yield
Non-qualified dividends are also taxed as ordinary income, therefore, the after tax yield of a non-qualified dividend that yields 8.8% = 5.544%
Qualified dividend pay a lower tax rate, since they are taxed as long term capital gains. If the after tax yield will be the same, then:
5.544% = dividend yield x (1 - 20%)
5.544% / 0.8 = dividend yield
6.93% = dividend yield