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21. Challenge Problem: Suppose that the yield curve on bonds that are free of the risk of default is flat at 5% per year. A 20-year default-free coupon bond (with annual coupons and $1,000 face value) that becomes callable after 10 years is trading at par and has a coupon rate of 5.5%. a. What is the implied value of the call provision? b. A Safeco Corporation bond that is otherwise identical to the callable 5.5% coupon bond described above, is also convertible into 10 shares of Safeco stock at any time up to the bond's maturity. If its yield to maturity is currently 3.5% per year, what is the implied value of the conversion feature