Hi,
As others have explained, because the GMAT is computer adaptive, it matters less how many you get right or wrong, and more what level the questions were that you got right or wrong. So, if you get a 300 level question right it means less in terms of raising your score than if you get a 700 level question right.
Since the experimental questions on the GMAT don't count, if they ask you an experimental question, your score will stay the same whether you answer it correctly or not.
Therefore, taking into account the 50 point standard deviation on our
MGMAT CATs, you should be able to accurately judge your skill level.
You may want to read this article on "How the GMAT Finds Your Score" for more info:
https://www.manhattangmat.com/strategy-series-gmat-score.cfmBest,
Caitlin Clay
Student Services Associate
Manhattan GMAT