Based on the free press article, the math worked out to 274 of the 2039 ED2 apps would get accepted.
http://dailyfreepress.com/2017/01/19/look-incoming-class-2021-early-decision-students/
42% ED acceptance rate for the first early decision round. Not 42% overall ED. If that were the case, 1700+ kids would get accepted and the articles says a total of 1190 from ED1 and ED2 will be accepted. The article jumps around a bit but the numbers seem to be:
~4181 ED 1 and 2 apps (this number is provided in the article
~2142 ED1 apps (this # assumed)
~2039 ED2 apps (this # is provided in the article)
916 of 2142 accepted = 42%
1,190 will enroll from ED1 and ED2
274 slots left to be admitted from ED2 (274/ 2039 = 13%)
3500 freshman class/ 35% enrolled ED1 & ED2 is 1190.