Hi speedrevision37,
How are you currently performing on the OVERALL Quant section? I ask because Probability is one of the rarer subjects on Test Day (there's a reasonable chance that you'll see just 1 Probability question), so it isn't a big 'point gainer.' By extension, if you're not already great at all of the big-point categories, then your time might be better spent on other areas.
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied? How many hours do you typically study each week?
2) What study materials have you used so far? What “brands” of CATs/mocks have you used?
3) On what dates (or approximate dates) did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your overall goal score?
5) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich