I'm not saying everybody in the world that is over a certain age will have trouble in college. That is obviously not true. I'm just going by what I noticed in my older undergraduates during the time I taught statistics. Like I mentioned elsewhere, maybe it's just an issue with statistics classes. I don't think it's out of the realm of possibility that a lot of older students may have forgotten key parts of their high school education. Again, I'll stress that not everybody over a certain age will have trouble, but in my experience teaching stats at one university a trend emerged. Maybe it's different elsewhere or in other classes