$6\mathrm{.}9$ Find the coupon rate of a $5-$year $$100$ par semiannual coupon bond redeemable at par, yielding $5\mathrm{.}7\%$ convertible semiannually, if its price is the same as that of a zero$-$coupon bond with face value $$100$ maturing in $5$ years and yielding $3\mathrm{.}5\%$ compounded annually.