I am not currently enrolled in any university (too costly for me at this time), but I would like to study as much as I can in various subjects (Advanced Mathematics, Psychology, Computer Programming and so on.) I'd like to find out the areas in which I am adept in case I decide to attend a university later on in life. This will prevent me from working towards an area that I may not be good at or a line of work that I ultimately find out I'm not interested in (both of which have happened to many people I know.)
Are there any universities that provide past curriculums and exams (with answers) online to be used as study guides?