Finance
posted by granann .
My uncle Samuel has $450,000 invested at 6.5%, and he plans to retire. He wants to withdraw $40,000 at the beginning of each year, starting immediately. How many years will it take to exhaust her funds, run the account down to zero?

450000=40000 + 40000(1  1.065^n)/.065
I am using
PV = Paym(1  (1+i)^n)/n
but ....
that formula assumes that payments are made at the end of the period, which explains the single 40,000
.66625 = 1  1.065^n
1.065^n = .33375
log both sides
n(log 1.065) = log .33375
n = 17.425
n = appr 17.4 years
(not many years of retirement with money, I have already been retired for 17 years and hope to have lots left. )