SOLUTION: This is a word problem.Three years ago, I depsited $600.00 in my account, and now I have 708.00. What is the interest rate on my account?

A = P(1 + )nt

A = ending amount = 708
P = beginning amount = 600
r = rate expressed as a decimal (what we are to find)
n = number of times a year the interest is compounded.  
    This is not given, so we assume it to be 1, once a year.
t = time in years = 3

708 = (600)(1 + )((1)(3))

708 = 600(1 + r)3

Divide both sides by 600

 = (1 + r)3

1.18 =  (1 + r)3

Take cube roots of both sides:

1.056721805 = 1 + r

Subtract 1 from both sides

.056721805 = r

As a percent that's 5.6721805%

Edwin