PMT=PV. R.{[1 + R]^N/ [1 + R]^N - 1}
170.22 =8,200 x R {[1+R]^60 / [1+R]^60 - 1}
0.020758536= R*{[1+R]^60 / [1+R]^60 - 1}, solve for R
There is no DIRECT solution for R (interest rate), but through iteration and interpolation, the computer gives a rate of 9% compounded monthly.