In the past, the mean score of the seniors at North High ACT exam has been 20. This year a special preparation course is offered, and all 120 seniors planning to take the ACT test enroll in the course. The mean of their 120ACT scores is 21.5. The principal believes that the new course has improved the students' ACT scores. Assume that ACT scores for seniors at North High vary Normally with standard deviation 5. Alpha =.05 a. State the question you would like to answer, your null and alternative hypotheses b. Calculations: Include z score and p-value c. Conclusion: Rejection decision, why, and answer to the question.