What is the duration of a bond with four years to maturity and a coupon of 8 percent paid annually if the bond sells at par? What is the duration of a bond with two years to maturity if the bond has a coupon rate of 7 percent paid semiannually, and the market interest rate is 5 percent? I have set up tables to do this, but I am not coming out with the correct PV calculation. Please provide the actual values used to compute PV. Here is where I am on the first part.

What is the duration of a bond with four years to maturity and a coupon of 8 percent paid annually if the bond sells at par?
Price of bond=face value=	$1,000
Yearly cash flow from the bond	8%
Relative value of each payment = PV Payment/price of the bond
Contribution of each payment to the duration = Relative value X by years until payment occurs
Payment (R*facevalue)	Year	PV of payment
$80	1	74.77
$80	2	PV(8%, ?, ?)
$80	3	PV(8%, ?, ?)
$1,080	4	PV(8%, ?, ?)
Duration = Total PV/par value
Duration = Total PV/Current price