I had trouble in this area as well in the beginning. I used the pdf file in the wiki on permutations, combinations and probability and it seemed to help a lot. All of the questions in the file have explanations which is nice. I felt that the harder problems from the file were much harder than anything on the actual GMAT test. I haven't gotten a permutation/combination problem wrong in the OG for a while now.
I can't find it right now, but I'm sure someone else can post a link.
Hope that helps.
I can't find it right now, but I'm sure someone else can post a link.
Hope that helps.
rwrangler












