A 30-year maturity, 6% coupon bond paying coupons semiannually is callable in five years at a call price of $1,100. The bond currently sells at a yield to maturity of 5% (2.5% per half-year).

a. What is the yield to call? 

b. What is the yield to call if the call price is only $1,050? 

c. What is the yield to call if the call price is $1,100 but the bond can be called in two years instead of five years?