Hi luukb22,

Each person (depending on his/her target score) will have different goals/standards regarding the % of correct responses to questions in the Official Guide. It's hard to say how 80% translates to an actual test score since you may have spent a lot of time on those questions. Also, the computer adaptive nature of the GMAT ensures that you see only those questions that are on the edge of your abilities, whereas the OG contains both questions that are well beyond your skills and questions that are beyond your skills.

I suggest that you use relative frequencies to identify your weaknesses. For example, if you correctly answered 95% of all Statistics questions and only 50% of all Geometry questions, then you should work on your Geometry skills.

Cheers,
Brent