Hi Hugo1987,
To answer your immediate question: YES - you can hit 700+ without answering the Probability and Combination questions correctly - but that does NOT mean that skipping those subjects is a good idea. Standard Probability, Permutation and Combination questions are actually fairly straight-forward questions (the math involved isn't that difficult), so you would end up potentially skipping past some 'gettable' questions if you were to proceed with that plan.
From your other post, I know a little bit about your prior studies, but 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 did you typically study each week?
2) What study materials have you used so far?
3) How have you scored on EACH of your CATs/mocks (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) When are you planning to take the GMAT?
5) When are you planning to apply to Business School?
6) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich