The formula for yearly annual interest is A = S(1+r)^t
A is the answer. S is the given amount, AKA the starting amount. r is the rate in which it increases or decreases. It increases because you add 1 to the rate. If you were to decrease the amount, then of course you would subtract 1 from the rate. t is the amount of years that have gone by.
Now we must substitute the given numbers.
A = 500(1 + .05)^15
The .05 came from dividing the rate by 100, since it is 5 percent. If it's percent, the number is always divided by 100.
You get a calculator and the answer will be 1039.46.
$1039.46 is the amount of money she would come across by.
