A Health Researcher Conducted an Experiment in Which Participants Watched

A health researcher conducted an experiment in which participants watched a film that either did or did not include a person being injured because of not wearing a seat belt. A week later, as part of a seemingly different study, these same participants reported how important they thought it was to wear seat belts. The 16 participants who had seen the injury film gave a mean rating of 8.9 with an estimated population standard deviation of 2.1. The 36 participants in the control condition had a mean of 7.0 with an estimated population standard deviation of 2.4. Do these results suggest that seeing a movie with a person being injured due to not wearing a seat belt makes attitudes more positive (higher ratings)toward seat belt usage? (Use the .01 level.)
a. Use the five steps of hypothesis testing.
b. Sketch the distribution involved.
c. Figure the effect size.
d. Explain what you did to a person who is familiar with the t test for a single sample but is unfamiliar with the t test for independent means.