Question

interest formula, and or answer. if you put $200.00 in an annuity that grows at 6% interest per year at the end of every year, and you add $200.00 more at the end of every year, how much will you have at the end of 70 years.
I know prt, but it doesn't work. is this pertaining to the geometric formula of Sn=[n(A1+An)]/2

Answer 1

You want

200((1.06^71 - 1)/(1.06-1) - 1)

Better study your annuity formula and how it arises.