I tried doing this, but I can't seem to make a formula that will work.

The formula for the simple interest earned on an investment is I=prt, where I is the interest earned, p is the principal, r is the interest rate, and t is the time in years. Assume that $5000 is invested at the annual interest rate of 8% and that the interest is added to the principal at the end of each year.

a. Find the amount of interest that will be earned each year for five years. I came up with the formula of I = 5000(.08)(t) but that doesnt work how it should.

b. State the domain and range of the relation. I'm not too sure about what would domain and range would be in this specific problem.

c. Is this relation a function? Why or Why Not? I say yes it is a function, because logically there shouldn't be 2 items that begin with the same number.
Thanks

Dimava