Article: The waiting room principle « God plays dice

The waiting room principle « God plays dice
http://gottwurfelt.wordpress.com/2012/02/18/the-waiting-room-principle/

Another educational example is that by simply making all classes at an institution the same size, one can reduce the average class size experienced by students without actually having to hire more faculty. Say your institution has one class of thirty students and one of sixty. Then if you pick a student uniformly at random, one-third will say "there are thirty students in my class" and two-thirds will say "there are sixty students in my class", for an average of (1/3)(30)+(2/3)(60)=50. If you rebalance the classes to have forty-five students in each class, then the average class size experienced by students is 45. (The average class size experienced by students, by the way, is always greater than or equal to the average class size experienced by instructors, with equality if and only if all classes are the same size.)

---SPSmith