Final answer:
Joseph should invest in treasury bills at 6.5% interest compounded annually because it will yield a higher future value compared to the money market account.
Step-by-step explanation:
To determine whether Joseph should invest in treasury bills or a money market account, we need to compare the future values of these two investments after twenty years.
Case 1: Treasury Bills at 6.5% interest compounded annually
Future Value = Principal * (1 + interest rate / number of compounding periods) ^ (number of compounding periods * time)
Future Value = $8,000 * (1 + 0.065/1) ^ (1*20) = $21,517.96
Case 2: Money Market Account at 6% interest compounded monthly
Future Value = Principal * (1 + interest rate / number of compounding periods) ^ (number of compounding periods * time)
Future Value = $8,000 * (1 + 0.06/12) ^ (12*20) = $21,026.23
Therefore, Joseph should invest in treasury bills at 6.5% interest compounded annually because it will yield a higher future value of $21,517.96 compared to $21,026.23 from the money market account.