Anyone have a good site to explain the tree for probability?

It’s just not clicking.

can’t really think of any but i can show you an example i showed someone else a couple of days ago ------------------------------------------------------------------------------------------ How do you answer this question? --------- In Favour Against CFA Charterholders --------- 235 765 CFA Candidates --------- 180 820 Given the information that a member of the group is in favour of a continuing education requirement, what is the probability that she is a CFA Candidate? A) 37% B) 43% C) 50% D) 57% you don’t really need a tree for this question but if you were to use one, this is what it would look like

Thanks. I think I just need to go to Schweser and load up on these.