Is it realistic to expect more than 610?

Assuming that the 530 is anywhere near your true score, I would concentrate far more on the geometry questions than combinations. Remember that a score of 530 is near the center of the distribution- you need to emphasize the basics rather than the questions intended to discriminate among students at the far right tail.

I have taken the Kaplan and the princeton review. Couple of areas of concern that I have are: -

1. I have gotten 560 in the first Kaplan exam, 570 in the 2nd Kaplan Exam.
2. After that I gave the Princeton Review exam and I got a 500 and part of the problem I attribute it to is time management. I did not manage my time effectively. But after that I have not scored anywhere close to 570 or 560 or any improvement in the score. It has been frustrating since I am running out of time and I want to apply for a Part time MBA program (Weekend MBA) and the timelines for those are close to March end time frame. With this score in my practice exams and my choice of school that I wish to apply to, it almost seems uncertain if I will be able to get into the school of my choice.

Which is the best book for Geometry that I can refer to. Please let me know.

Thanks,

Axl_OZ

A good place to start is the description of the Q section in the OG. Read it carefully and make certain that you understand the scope of coverage.