According to Money, the average yield of a 6-month bank certificate of deposit (CD) is 3.56%, and the average yield for money market funds (MMFs) is 4.84%.
Assume that these two averages come from two random samples of 20 each from these two kinds of investments, and that the sample standard deviation for the CDs is 2.8% and for the MMFs it is 3.2%.
Use statistical inference to determine whether, on average, one mode of investment is better than the other.