You can put this solution on YOUR website!
looks like you started off ok.
your formula is:
S = P * (1+i)^n
you used 10,000 for P and 1.21 * 10,000 = 12100 for S.
that's correct but not necessary because you could just as easily have used 1 for P and 1.21 for S.
I don't know why you filled in 4 for n.
if compounding is annually, then n should have been 2 to represent 2 years.
using your numbers for S and P, your formula should have become:
12100 = 10000 * (1+x)^2
x is the annual interest rate.
divide both sides of this equation by 10000 to get:
1.21 = (1+x)^2
take the square root of both sides of this equation to get:
subtract 1 from both sidesof this equation to get:
solve for x to get:
x = .1
looks like you are looking for 10% a year growth compounded annually for 2 years.
to confirm, substitute in your original equation to get:
12100 = 10000 * (1+x)^2 becomes:
12100 = 10000 * (1.1)^2
simplify to get:
12100 = 12100 confirming the answer is good.