For each of the following situations determine whether a one- or a two-tailed test is appropriate. Also, state the research and the null hypotheses.
a. You are interested in finding out if the average household income of residents in your state is different from the national average household. According to the U.S. Census, for 2011, the national average household income is $50,054.
b. You believe that students in small liberal arts colleges attend more parties per month than students nationwide. It is known that nationally undergraduate students attend an average of 3.2 parties per month. The average number of parties per month will be calculated from a random sample of students from small liberal arts colleges.
c. A sociologist believes that the average income of elderly women is lower than the average income of elderly men.
d. Is there a difference in the amount of study time on-campus and off-campus students devote to their schoolwork during an average week? You prepare a survey to determine the average number of study hours for each group of students.
e. Reading scores for a group of third graders enrolled in an accelerated reading program are predicted to be higher than the scores for non-enrolled third graders.
f. Stress (measured on an ordinal scale) is predicted to be lower for adults who own dogs (or other pets) than for non-pet owners.