15 hours of classes + 2-3 hours of study time per hour of class time, figure 40 hours on average for 55 hours of work per week. Not too bad, until you factor in your first year writing seminar, which can easily add another 10-15 hours per week. So, figure about 70 hours per week if you want to do well, and increase that by a 30% in the 2-3 weeks before exams.