income tax period (typically April 10 to April 15). researcher's contention. H0: is Ha: is decimals)? c. Using =0.05, can you conclude that the population mean refund for "last minute" filers is less than the population mean refund for early filers? d. Repeat the preceding hypothesis test using the critical value approach. Using =0.05, what is the critical value for the test statistic (to 3 decimals)? Enter negative value as negative number. State the rejection rule: Reject H0 if z is the critical value. Using the critical value approach, can you conclude that the population mean refund for "last minute" filers is less than the population mean refund for early filers