Hi rajiskrish,
When it comes to the GMAT, improvement over the course of one's studies is rarely a 'linear' path. It's important to remember that the GMAT will give you the score that you EARN - and the V38 that you scored on Exam #3 appears to be an 'outlier' relative to the other scores (which forces the question - did you really 'earn' a V38 or did you get lucky on a bunch of 50/50 questions?). Assuming that you took these CATs in a realistic fashion that matches up with what you'll face on Test Day, it appears that your current 'ability level' is closer to a 640.
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?
2) What study materials have you used so far?
3) How have you scored on EACH of your CATs (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your goal score?
5) What is your exact Test Date?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich