please use excel to find the solution

$3.$ Bernstein Co$.$ issued $15-$year bonds $10$ years ago at a coupon rate of $3\mathrm{.}75$ percent. The bonds make semiannual payments and have a par value of $$1,000.$ If the YTM on these bonds is $2\mathrm{.}5$ percent, what is the current bond price?

$4.$ Northern Corp. issued $20-$year bonds three years ago at a coupon rate of $4\mathrm{.}25$ percent. The bonds make semiannual payments. If these bonds currently sell for $101\mathrm{.}50$ percent of par value, what is the YTM$?$