You should be able to pass.
But it depends on the exams. Lately they DO change exams, adding new questions.
Lately we had performance exam. They change a lot on it (added tons of new stuff, added some incorrect graphs where you was supposed to extend lines (illegal).
Anyhow. Guys who did ONLY QB got around 45-50. Those who did only QB, but was smart and at least was paying attention in the class, got 55-65.
Those who studied got 65-73.
No one passed that exam (worldwide!) and we got free re-set. But my point is. If you study and they add many new questions - you have better chances to pass.
All exams I took, they had 10-20 new questions. I did whole QB (for some subj. around 80-90% of QB) once and my avg is 93 now. And best part - I have knowledge that one day MAY save my life. Nice to have.