HCA has a corporate tax-rate of 40%. Given the detailed information below, what is HCA's weighted average cost of capital?.

a. Debt: HCA has 60,000 bonds outstanding; they currently trade at 109.5, have 20 years to maturity, and bear a coupon rate of 6%. Six years ago, the firm also issued 230,000 zero coupon bonds. When they were issued, they had 36 years to maturity; today they trade at 17.5.

b. Common Stock: When HCA did its IPO nine years ago, the firm issued 2.6 million shares of common stock. The Wall Street Journal reports that HCA's common shares have a beta of 1.15. The shares initially traded at $18.10 per share, trade today on the NYSE at $65, and have a par value of $3.40 per share.

c. Preferred Stock: Five years ago, HCA issued 83,470 preferred shares. Two years ago, the firm issued another 40,110 preferred shares. Last month, the firm issued an additional 26,420 of these 4% preferred shares. Though they have a book value of $100, they currently trade at $79.

d. Market Information: The market return is currently 11% and the market risk premium is 7%. Utilize this information to determine the relevant risk-free rate for the U.S. markets.