GMAT Strategy

So...I just took the second practice test that comes with registration for GMAT.

I have gotten pretty good scores both times, BUT I always feel like I've bombed QUANT after that section. Although I can make educated guesses and sometimes know the answer cold, for 75% of the questions I am not very sure of my answer. After this last test, I got 27 out of 37, which translated to a 48. However, I missed 2 of the first ten and THE LAST SIX QUESTIONS (but not many in between, obviously).

I don't really have any issues with verbal, I got 38 out of 41, which translated to a 47.

Overall, this score was 760 and last score was 720.

I can't help but feel like I am getting lucky or it is not scoring correctly.

So, after all that buildup, my question is for people who have taken the actual test:

ARE THESE TESTS AN ACCURATE PREDICTOR OF PERFORMANCE?

To be short, yes. The GMATPrep tests are the most accurate CATs available.