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Question

Four years ago you invested some money at 10% interest. You now have 439.23$ in the account. If the interest was compounded yearly, how much did you invest 4 years ago?

Accepted Answer

Let x be the initial amount. After four years, at a ten percent annual interest rate, the investment will have grown to x 1.1^4, so x 1.1^4 = 439.23. Then x = 439.23/1.1^4 = 300.