Aphid Corp. will finance its next major expansion with $60\%$ debt, $10\%$ preferred stock, and $30\%$ retained earnings. Aphid$$s after$-$tax cost of debt is $4\%,$ cost of preferred stock is $7\mathrm{.}4\%,$ and cost of retained earnings is $11\%.$ What is the corporation$$s weighted average cost of capital? Submit your answer as a percentage and round to two decimal places $($Ex$.0\mathrm{.}00\%)$