The Survey of Study Habits and Attitudes (SSHA) is aphychological test that measures the motivation, attitude towardschool, and study habits of students. Scores range from 0 to 200.The mean score for U.S. college students is about 115, and thestandard deviation is about 30. A teacher who suspects that olderstudents have better attitudes toward school gives that the SSHA to25 students who are at least 30 years of age. Their mean is ¯x =127.8.
(a) Assuming that ? = 30 for the population of older students,carry out a test of
H0 : µ = 115
Ha : µ > 115
Report the P-value of your test, and state yourconclusion clearly.
(b) Your test in part (a) required two importantassumptions in addition to the assumption that the value of ? isknown. What are they? Which of these assumptions is most importantto the validity of your conclusion in part (a)?
