General Electric has just issued a callable$($at par$)10-$year, $6\mathrm{.}4\%$ coupon bond with annual coupon payments. The bond can be called at par in one year or anytime thereafter on a coupon payment date. It has a price of $ $101\mathrm{.}64.$

a$.$ What is the$$ bond's yield to$$ maturity?

b$.$ What is its yield to$$ call?

c$.$ What is its yield to$$ worst?