<p>If you want to go to graduate school though, know that you’ll have to convince admissions people that you’re just as qualified as those who were doing only one of the fields. I certainly know one grad student at my school, which is one of the top ranked math programs, who went to MIT and studied EECS, economics, and math. But that takes a prodigious effort and interest in each of the fields to keep up. If you find yourself leaning any given way, make sure to do the one that you’re leaning towards very well, and you’ll make it.</p>