JCH wrote...
....
Q: Consider a bond with a face value of $1,000. The coupon payment is made
semi-annually and the yield to maturity is 12% (effective annual yield). How
much would you pay for the bond if:
A: The coupon rate is 8% and the time to maturity is 20 years?
B: The coupon rate is 10% and the time to maturity is 15 years?

Use the PRICE function. It's provided by the Analysis ToolPak (ATP),
which isn't loaded by default. See online help for the PRICE function
to find directions for loading the ATP.