GMAT Strategy

I understand your frustration. My advice is to not read into your test prep scores too much. At best, they can provide you a high-level idea of how you are progressing through your studies, but no practice test (other than GMATPrep, maybe) can accurately predict your scores.

Instead, focus on your errors and try to analyze why you got certain questions wrong. Figure out your weaknesses and make them your strengths--this is a more productive use of your time than trying to figure out a scoring algorithm.

Best of luck!