(Isn't 'codswallop' a fun word?)
OK, so all over the internet (and IRL, too) I've seen the 47% or "slightly under half" Jewish stat bandied about. It seems to come from this Hillel site (http://www.hillel.org/college-guide/list/record/brandeis-university
). People use it in a multitude of ways - to argue that Brandeis isn't all that Jewish, or is really Jewish, or whatever.
Now, quite apart from the question of whether the amount of Judaism in a school should really be that big a deal, I'm pretty sure this number is fiction.
Brandeis doesn't keep track of religion, but it does keep track of race. Over here (http://www.brandeis.edu/about/facts/schools.html
) we see that the school is 46.9% white.
If 47% of Brandeis is Jewish, literally every. single. white kid on campus HAS to be Jewish - and even then, it still wouldn't be enough. Given that I know a bunch of white gentiles just from my tiny school considering Brandeis, I find this extremely unlikely.
(Also: It's true that it's possible for non-whites to be Jewish, but as a Jew who has met a lot of other Jews, I feel fairly confident in stating that the vast majoirty of Northeast Jews are white, and for the purposes of Brandeis non-white Jews are not going to be present in enough numbers to make the 47% statistic make sense.)
So, it seems that Hillel is inflating their numbers a least a little, and probably a lot. I'd make a WAG that at most, Brandeis is maybe 25 to 30% Jewish - and even then, that would leave only 17% for non-Jewish whites, which seems a little low. And that's not even factoring in that this is probably considering people who have a Jewish mom but can't tell a menorah from a seder plate Jewish.
In short: if you're hesitant about Brandeis because you think it'll be Hebrew school all over again, chill out.