Hi aabhish,

The scoring algorithm on the Official GMAT is far more complicated than most people realize. It takes into account a number of different factors, including the relative difficulty of the question, whether you were expected to get it correct or not, the placement of the question, what's going on "around it", the "strings" of correct and incorrect answers, whether the question even counts or not (some questions are "experimental" and are worth 0), if you leave questions unanswered and incur a penalty, etc. As such, you shouldn't be spending time trying to figure it all out. You'd be better served working on building up your skills.

Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT scores can vary a bit based on the 'biases' involved in their respective designs. Your scores are all 'in range' of one another though, so assuming that you took the ENTIRE CAT and did so under realistic 'test-like' conditions, then these scores serve as a reasonably accurate assessment of your abilities.

A far more useful gauge would be to review each CAT and determine how many questions you SHOULD have gotten correct, but didn't (due to a silly/little mistake). Those mistakes are the things that you have to fix to score at a higher level.

GMAT assassins aren't born, they're made,
Rich