A political scientist is interested in the question of whether or not there is a difference between Republicans and Democrats when it comes to their involvement in voluntary associations. Using a 25 point scale to measure involvement in voluntary associations, and collecting information from a random sample of 22 Republicans and 17 Democrats, he/she discovers the following: Republicans: Mean of 12.56 with a standard deviation of 3.77 Democrats: Mean of 16.43 with a standard deviation of 4.21 Assume that you're working at the .05 level of significance.
a. Formulate an appropriate null hypothesis.
b. Calculate t statistic.
c. Identify the critical value.
d. State your conclusion.