Q133. College is a more or less four year endeavor but students come and go on different schedules. Sketch a stock and flow model that shows freshwomen applicants coming from the cloud, admitted students from applicants, and freshwomen from the admittees. Then freshwomen become sophomores, mostly, but there is some attrition. And so on through the other years. Sketch a stock and flow diagram that follows students through four years and think up some variables that might affect the flows between the different years. For this problem, you should try wearing the hat of an academic administrator who is interested in the problems of "retention" and "degree completion."