Annuities
It refers to a special form to accumulate interest over a regular payment or cash flow (C) per period.
Devon decides to save money for her retirement by depositing C=$524 each month in an account that is expected to earn interest with an APR of r=5.25% compounded monthly.
We will calculate the future value (FV) of her investment over a period of n=40 years.
The future value can be calculated with the formula:
![FV=C\cdot((1+i)^n-1)/(i)](https://img.qammunity.org/2023/formulas/mathematics/college/wlui8pmvwv02yn1kmsnmkzv8grk0hrr8qg.png)
Where i is the interest rate adjusted for the compounding period. Since there are 12 months in one year:
![i=(r)/(12)=(0.0525)/(12)=0.004375](https://img.qammunity.org/2023/formulas/mathematics/college/x502j7tcdk4gdm1u7yo558nht31uf57n3m.png)
The number of periods is also adjusted for monthly compounding:
n = 40*12 = 480
Now apply the formula:
![FV=524\cdot((1+0.004375)^(480)-1)/(0.004375)](https://img.qammunity.org/2023/formulas/mathematics/college/dnb3feke7me2qr2953l5fa7w8ubt1vqowd.png)
Calculating:
![\begin{gathered} FV=524\cdot1,629.45 \\ FV=853,832.69 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/jgpznubh18y6dxmyc4xqtn86kk82630688.png)
There will be $853,832.69 in Devon's retirement account in 40 years