sos I can't figure this one out

Question

Andrea, a self-employed individual, wishes to accumulate a retirement fund of $800,000. How much should she deposit each month into her retirement account, which pays interest at a rate of 2.5%/year compounded monthly, to reach her goal upon retirement 35 years from now? (Round your answer to the nearest cent.) 

Answer 1

The "sinking fund" formula will find the payment amount, m:

m = A * i / [ (1 + i)^N - 1 ]

where

m is the amount of the periodic payment

A is the amount desired in the future

i is the interest rate per period = .025/12 for this problem with monthly compounding

N is the total number of payments = 35 * 12 for this problem (monthly for 35 years)

This formula is found by solving the annuity formula for the payment amount. The annuity formula is:

A = m * [ (1+i)^N - 1] / i

The variables are the same as defined above.

The payment amount will be a little under $1200 per month. (The total paid in over 35 years is a little over $501,000, fyi.)