The Tom Corp wants to know its cost of capital. Its current capital structure calls for $45\%$ debt, $15\%$ preferred stock and $40\%$ common equity. Initially, common stock will be in the form of retained earnings. The costs of the sources of financing are: debt: $5\mathrm{.}5\%$; preferred stock: $7\mathrm{.}4\%$; retained earnings: $10\%$; and new common stock, $11\mathrm{.}4\%.$  What is the weighted cost of capital? Use $2$ decimals.