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its also not a very hard statistical formula. I believe just about anyone whose taken statistcs at University should be able to do.

Basically, you are trying to find the Future value of an Annuity (or "amount" value). Take into consideration monthly payments (12payments/year), for 10 years. The compound amount of the last payment (what you have after 10 years) is S, and that you are making "n" paymments, at interest rate r, and each payment is "R".

Then the formula is:
S = R * [(1 + r)^n - 1]/r

Therefore, assume you are investing monthly payments of $50, at a rate of 15% per year, compounded monthly.


R = 50
r = .15/12 = 0.0125 (divide by 12 because you are "compounding" 12 times throughout the year).
n = 12(10) = 120 payments all togehter

Then, working it out..

S = 50 * [(1.0125)^120 - 1]/0.0125
works out to:

S =
$ 13,760

Therefore, if you invest $50/month for 10 years, at a rate of 15%/year, you will have after 10 years $13,760 (with an investment of 50*120 = 6000).

So, essentially you make $13760 - 6000 = $7760 after 10 years.

Hope it makes some sense :)

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