The "major schools" you talk about are probably private
unis.
Try the three local unis, most of the students are around 21,
give or take a few years.
For your information, the 3 local universities here are National
University of Singapore (NUS), Nanyang Technological University
(NTU) and Singapore Management University (SMU). All three are
good, though you would probably be most interested in SMU as they
have very good business/entrepreneurship programmes from what I've
heard, so I would recommend that you check them out even though I
would like to support my alma mater NUS.