statistics
posted by Mathew .
6. A geography student needs to take three 300 level and three 400 level geography classes next semester in order to graduate. If there are 10 300 level courses being offered and 7 400 level courses being offered, how many different schedules could the student have?

Using the Hypergeometric Rule
C_3^10*C_3^(7 )= 10!/3!(103)! * 7!/3!(73)! = 120(35) = 4200