Individuals filing federal income tax returns prior to March 31 received an average refund of $1056. Consider the population of "last-minute" filers who mail their tax return during the last five days of the income tax period. a. A researcher suggests that a reason individuals wait until the last five days is that on average these individuals receive lower refunds than do the early filers. Develop appropriate hypotheses such that the rejection of Ho will support the researcher's contention. b. For a sample of 400 individuals who filed a tax return after April 10th, the sample mean refund was $910. Based on prior experience a population standard deviation of sigma = $1600 may be assumed. What is the p value? Use an alpha level of .05.