Thanks for your response Brent.

I agree that practice test is a better indication of your performance, but I just wanted to get an estimate of how accurate people are while solving these, of course under timed conditions. I solve 10 questions at a time and on an average take less than 2 minutes for each question, but I make silly errors which has nothing to do with concepts.

I read somewhere that you can still get a great score (700+) with about 60-70% accuracy on the actual GMAT, wanted to get some data to decide before believing in it.

Agree with Brent on this and probably that's why the percentage accuracy is no indicator of the range of score that you may get in actual GMAT.

However much I wanted to know the same, the percentage accuracy is again a blend of Math & Verbal scores ( which again might be varied individually) added numerically, lack of the real exam stress & the normalization that comes with level of difficulty for the questions.

It may be possible that the you are doing good if most of your questions in the end are going right. They say that the difficulty level in general increases as you approach the end. I'm not sure how true that is , for I've felt a uniformity in the difficulty level for all questions.