Please help with the wrong answer.

The Omega Corporation has some excess cash It would like to invest in marketable securities for a long-term hold. Its Vice-President of Finance is considering three Investments: (a) Treasury bonds at a 6 percent yield; (b) corporate bonds at a 11 percent yleld; or (0) preferred stock at an 8 percent yleld. Omega Corporation is in a 40 percent tax bracket and the tax rate on dividends Is 10 percent. a-1. Compute the aftertax ylelds for the three Investment options. (Do not round Intermediate calculations. Input your answers as a percent rounded to 2 decimal places.) Answer is complete but not entirely correct. a. Aftertax yields 3,60 % 6,60 % Treasury bonds Corporate bonds Preferred stock b 7.20 %