The interest rate offered by bank is ultra low right now, however, if you invest your money into S&P 500, you are expected to get a reasonable return on average each year. Check the average return for S&P 500 in the past, use this return rate as your i. If you put $1000 into your account today, how much money you will have after 40 years using: a) a simple interest b) a compound interest? Your answer will differ depends on the time frame (how many past year) you choose to calculate the average return.