Sheridan Co. has a capital structure, based on current market values, that consists of 50 percent debt, 10 percent preferred stock, and 40 percent common stock. If the returns required by investors are 9 percent, 11 percent, and 15 percent for the debt, preferred stock, and common stock, respectively, what is Sheridan's after-tax WACC? Assume that the firm's marginal tax rate is 28 percent. (Do not round intermediate calculations. Round answer to 1 decimal place, e.8. 15.2\%) After tax WACC %