My math works through a tad different. It seems that Exeter has over 1,000 students. Unless you assume they go cold turkey, and refuse financial aid to all but new Preps, I would use that number in my calculations. At least include new upperclassmen, as well, even if you neglect returning students! Using 1,000 students, 13% would be 130 students.
So $50k for 130 students is $6.5M. Using the $7.9M number cited above leaves $1.4M for the other students on aid. There would be another 33.3% of the students on partial aid, or about 333 students (although Exeter claims “fewer than 300” on their website). $1.4M for 333 students comes to about $4,200 per student. Checking, $7.9M over 463 students averages to $17K per student on aid, less than the $41.5 that Exeter cites. I saw that in 2011 Exeter gave out $15.853M in financial aid, or twice the cited $7.9M.
http://www.exeter.edu/exeter_bulletin/12984_14541.aspx
Somewhere in all of these numbers lies the truth. If we say 433 students received an average of $41.5K, that works out to $17.8M in financial aid, which is more believable. Subtracting $6.5M for those on Full aid gives $12.3M for ~300 students, or about $41K (82%) on average for each of the partial aid recipients.
So, @Heartburner used very different numbers than I did, but ultimately arrived at a similar result: ~$10K residual COA for “partial scholarship” recipients.
If you leave out tuition remission (e.g. faculty kids) students and day students, Exeter claims from its website: