all the best explanations are here, check all the problems related to C and P, analyze them and understand the solution for each kind of question.Then you will be able to ace the GMAT
For your information :
- on my 1st test I got 39 in Quant with a Combination
- on my last test (2 days ago) I got 48 in Quant without any C or P. Just 2 probabilities.
Actually you should study all the different subjects and be sure that you can answer to different type of question....but to score more than 46 in Quant you need to have a good knowledge of C/P and Probabilities because one of them will eventually come out