The present value (price) formula for a coupon bond is:
PV = C/(1+i) + C/(1+i)^{2} + ... + C/(1+i)^{n} + F/(1+i)^{n}
Part a
The present value (price) formula for a zero coupon bond is:
PV = F/(1+i)^{n}
Plugging in the given information,
Price = $1000/(1+0.1)^{15} = $239.39
Thus the price of the fifteen-yr zero coupon bond is $239.39.
Part b
Semiannual coupon = 6%*$500/2 = $15
Price = $15/(1+(0.1/2)) + $15/(1+(0.1/2))^{2} +..... + $15/(1+(0.1/2)^{6} + $500/(1+(0.1/2)^{6 }= $449.24
Thus the price of the three-yr semiannual 6% coupon bond is $449.24.