7. Babcock vey data from 2003-2005, and obtained an average of u = 14 hours per week spent studying by full-time students at four-year colleges in the United States. To determine 01, whether this average has changed in recent years, a researcher selected a sample of n - 64 of today's college students and obtained an average of M = 12.5 hours. If the standard deviation for the distribution is o = 4.8 hours per week, does this sample indicate a significant change in the number of hours spent study- ing? Use a two-tailed test with a - .05. an 8. Childhood participation in sports, cultural groups, and youth groups appears to be related to improved self- esteem for adolescents (McGee, Williams, Howden- Chapman, Martin, & Kawachi, 2006). In a representa- ents tive study, a sample of n = 100 adolescents with a it- history of group participation is given a standardized is self-esteem questionnaire. For the general popula- S. le tion of adolescents, scores on this questionnaire form a normal distribution with a mean of u = 50 and a standard deviation of o = 15. The sample of group- participation adolescents had an average of M - 53.8. a. Does this sample provide enough evidence to con- clude that self-esteem scores for these adolescents of are significantly different from those of the general 1 a population? Use a two-tailed test with a = .05. ly b. Compute Cohen's d to measure the size of the use difference. ng c. Write a sentence describing the outcome of the are hypothesis test and the measure of effect size as it would appear in a research report. h- 9. The psychology department is gradually changing its curriculum by increasing the number of online course offerings. To evaluate the effectiveness of this change, MacBook Pro