# Math Help - Compound Interest Problem

1. ## Compound Interest Problem

Kathy deposits $10,000 in her retirement account, which compounds interest continually. If she has$19,600 in the account after four years, how much money will she have in the account after another two years?

I'm not familiar with the compound interest formula.

2. ## Re: Compound Interest Problem

The compound interest formula is \displaystyle \begin{align*} A = P \left( 1 + R \right) ^n \end{align*}, where P is your principal, R is your interest rate for each time period of compounding, and n is the number of time periods that the interest compounds over.

6. ## Re: Compound Interest Problem

You are given the amount after four years and the principle, so substitute into the equation to get the yearly interest rate. Then you can substitute the value of 6. You should find that if you keep everything in terms of exponentials and logarithms, that things will simplify, and so you won't need a calculator.

7. ## Re: Compound Interest Problem

A=P*e^rt
19600=10000e^4r
ln 1.96=ln e^4r
0.673=4r
r=0.168
change P to 19600 and calculate the new amount after 2 years