Studying Time for Biologists and Psychologists. Use the following information for Exercises 44–47: The National Survey of Student Engagement reported in 2012 that the mean number of hours spent studying per week for biology majors was 16.7, whereas the mean for psychology majors was 13.9. Assume that these are sample means from sample sizes of 100, and that the sample standard deviations were each 5 hours.