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 $8$ percent yield; $($b$)$ corporate bonds at a $11$ percent yield; or $($c$)$ preferred stock at an $9$ percent yield. Omega Corporation is in a $35$ percent tax bracket and the tax rate on dividends is $20$ percent.

a$-1.$ Compute the aftertax yields for the three investment options. $($Do not round intermediate calculations. Input your answers as a percent rounded to $2$ decimal places.$)$

Tresury bond is $5\mathrm{.}20($this is verified correct$)$

Corporate bond is $7\mathrm{.}15($this is verified correct$)$

Preferend stock?

I have tried: $7\mathrm{.}20,5\mathrm{.}85,$ and $3\mathrm{.}15($all of these according to the computer system that checks my work are wrong$)$