First, let's find the annual coupon payment on the bond given the following:

Par value of the bond is $1,000

FV = 1,000

The price of the bond is $847.44

PV = -847.44

Negative sign indicates cash out flow

Years to maturity, N = 15

Yield to maturity of the bond is 8.5%

I/Y = 8.5

So, we have:

FV = 1000

PV = -847.44

N = 15

I/Y = 8.5

CPT PMT

PMT = $66.628654

Annual coupon = $66.628654

The coupon rate on the bond = Annual coupon/FV

Using the values from above,

The coupon rate = 66.628654/1,000

The coupon rate = 0.066628654

The coupon rate = 6.6628654%