Hi Rahul,
The scoring algorithm on the Official GMAT is far more complicated than most people realize. Since the Test is adaptive, it takes into account a number of different factors - more than just the number of correct answers. As such, you can't 'isolate' an RC passage and define how it will be 'scored.' A far more useful gauge would be to review each CAT and determine how many questions you SHOULD have gotten correct, but didn't (due to a silly/little mistake). Those mistakes are the things that you have to fix to score at a higher level.
1) How long have you studied?
2) What materials have you used?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
4) What is your goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich