<p>I would speculate that roughly one-third of each Harvard graduating class has ambitions of attending medical school, which would come to approximately 550 students. (From my personal experiences interacting with other members of the freshmen class, I would estimate that roughly 40% find medical school to be their most likely post-undergraduate possibility.) The magna cum laude distinction usually hovers between 3.70 and 3.75, which currently encompasses the latter 15% of the top quintile. I am not aware of the relevant statistics for the summa cum laude honor (top 4%-5% of the class) but I would wager on something in the 3.86-3.90 range. But, of course, grades are not standardized across all concentrations at Harvard, with humanities and social science majors receiving higher GPAs overall than those concentrating within the physical, life, and numerical sciences. And with writing and foreign language requirements to supplement the more eclectic Core/General Education Curriculum, along with required courses among the various science disciplines (along with a mandatory foundation in mathematics), maintaining an exceptional GPA as a pre-medical student requires a highly extensive range of exceptional aptitudes that are not required of students who are able to complete a course selection that is more tailored to their specific academic strengths and interests. So in a representative sample of 550 students, roughly twenty would graduate with a 3.90 or above. However, for the pre-medical population, I would have to speculate that the figure is slightly less than ten.</p>
<p>^ Assuming that your estimate for the number of aspiring premeds in freshman year is close, the attrition rate in 4 (or 5) years is (550-300)/550 = 250/550=5/11.</p>
<p>The number 300, the number of applicants from this college, is from this link (for year 2009):</p>