Consider a 3% 100 par-value 15-year bond. Assume that this bond is callable at 109 at coupons 10 to 20 inclusive, at 104.50 at coupons 21 to 29 inclusive, and at 100 at the time of the final coupon. What price should the investor pay to guarantee himself a nominal yield of (a) 4% semiannually? (b) 2% semiannually?