Hello, thank you for taking the time to post your question!
For compounded quarterly you want to use the formula
FV = P(1 + r/n)^(nt) …. For the values on this question that becomes
FV = 480(1 + 0.08/4)^(4*3)
FV = 480(1.02)^12
FV = 608.76
So the future value there is $608.76 and the interest earned is 608.76 – 480 = $128.76
Then for the other part of the question where it’s the same length of time but now interest is compounded continuously you want to update the formula to be
FV = P*e^(rt)
FV = 480 * e^(0.08*3)
FV = 480 * e^(0.24) = 610.20
So you end up with slightly higher values of the future value being $610.20 and the interest earned being 610.20 – 480 = $130.20
I hope that helps you get moving in a better direction on this type of question! Feel free to reach out if you have any additional questions beyond that :)
Michael F.
12/03/13