Question

7. The Survey of Study Habitss and Attitudes (SSHA) is a psychological test that measures the motivation, attitude toward school, and study habits of students. Scores range from 0 to 200. The mean score for U.S. college students is about 115, and the standard deviation is about 30. A teacher who suspects that older students have better attitudes toward school gives the SSHA to 25 students who are at least 30 years of age. Their mean score is x = 127.8 (a) Assuming that o 30 for the population of older students, carry out a test of Ho 115 Ha 115 Report the P-value of your test, and state your conclusion clearly at a 0.05 (4) (b) Your test in part (a) required two important assumptions in addition to the assumption that the value of is known. What are they? Which of these assumptions is most important to the validity of your conclusion in part (a)? (4)

Answer 1

a to 200 scones range from mean-lls skd. deviation = 30 - n=25 sample mean t = 127.8 0-30 Hoil=115 Haulis - one sample z-test no known) X-0.05 rest statistic z a X-M 127.8 -115 (2= 2.13 ) >2.13) p-value = 1/2 720) = P(Z el-plZc213) Sl 0.9834 VE 0.0166 (P-value = 0.0166 P-value less than alpha Co.os) Reject to and conclude that mean . is increased (Molls) we need to assume that the population i Normally distributed and samples are taken at randory from population