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) towards seat belt usage? (Use the .01 level.)

Write the hypotheses (null and alternate).

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. Be sure you explain how this problem differs from a t test for a single sample. Your answer should consist mainly of a thorough explanation of the characteristics of the comparison distribution and the logic of all steps of figuring you did to determine those characteristics