<p>Whether it is ivy league, or nationally recognized (stanford, penn, georgetown, etc)
I think the lowest I've heard was 23 for penn.</p>
<p>These are middle 50% figures from online.
Stanford: 31-34
Penn: 30-34
Georgetown: 29-33
Duke: 30-34
Harvard: 32-35
Yale: 31-35
Brown: 29-34
Columbia: 32-35
Cornell: 30-33
Dartmouth: 30-34
Princetown: 31-35</p>
<p>Of course if there are other important factors (athletic scholarship, alumni parent, etc) someone with a much lower score could be accepted. </p>
<p>Hope that helps!</p>