math 11
posted by karen .
An investment earning simple interest rate of 1.10% per annum for a term of 5 years earned 82.50 in interest. What was the principal?

oh sry i forgot to ask these questions.. to help you answer this one its a long one
1.calculate the final value after 10 years if you invest 5000.0 at 2.5% compounded annualy
2.Calculate the amount of interest earned in 10 years on 1000.00 invested at 3.00% per annum, compounded monthly
3.calculate the interest due on the following credit card balanced
a)an unpaid balance of 1629.53 at a rate of 19.50% for 21 days
b) an unpaid balance of 2639.99 at a rate of 22.95% for 30 days. 
I got $87.04