qusiba

I'm going back to university this September and I picked up a course which has some prerequisites

Mathematics & Statistics (Sci): Sample space, events, conditional probability, independence of events, Bayes' Theorem. Basic combinatorial probability, random variables, discrete and continuous univariate and multivariate distributions. Independence of random variables. Inequalities, weak law of large numbers, central limit theorem.

I've studied statistics many years ago but as I don't use it in my work I completely forgot all of it. Since there're still a month before September, I think I should make some preparation for my study if I don't want to drop the course. So is there any good Internet studying resources that I can use to refresh my statistic knowledge? (I thought about buying textbooks, but they are really expensive)