A university president believes that, over the past few years, the average age of students attending his university has changed. To test this hypothesis, an experiment is conducted in which the age of n=121 students who have been randomly sampled from the student body is measured. The mean age is M=22.9 years. A complete census taken at the university a few years before the experiment showed a mean age of =25.3 years, with a standard deviation of =8.8.

Answer the following questions based on the above scenario.

State the study hypotheses (using sentences or annotations)

1. Using a two-tailed test with = .05, is the data sufficient to conclude that the average age of students in the university has changed? In your answer, state (1) the boundaries of the critical region, (2) the test statistic for your sample and, (3) your decision.

1. Compute Cohen's d for this study

1. What if the researcher had used a two-tailed test with = .01? In your answer, state (1) the boundaries of the critical region, (2) your decision.

1. What if the researcher had predicted an increase in students' ages and decided to use a one-tailed test with = .05? In your answer, state (1) the boundary of the critical region, (2) your decision.

1. What if the researcher had predicted adecreasein students' ages and decided to use a one-tailed test with = .01? In your answer, state (1) the boundary of the critical region, (2) your decision.