Tapas,
I am going to have to disappoint you, because there is no perfect way in which to assess whether you are ready for the PMP exam or not. Some people read the PMBOK Guide once and then go and pass the exam without any further study. Not recommended, but it's been done. And then others study for hours at end, do a thorough preparation and then they fail in the exam.
The only real way to know is to actually take the exam and pass. Unfortunately.
However... that much said I can tell you that from anecdotal feedback that most of our customers who use the simulator and get over 80% in their first results do report back that they have passed. (Note that your own results may vary.)
The only explanation that I have regarding why you are getting lower scores on free questions from other sources is that these free questions may still be based on the previous PMBOK Guide, or that you have answered the questions from Oliver Lehmann, which are terribly difficult and even I can hardly get 50% of those right.
So the only thing that you can do is to review your own studies. Think about the following: Do you think that you studied hard enough? Do you think that you comprehended the concepts from the PMBOK Guide? How does your preparation compare to lessons learned from others? What might be the reason behind your lower score on other questions?
And most importantly: Do you personally feel ready?
If you answer the last question with Yes then all that remains for you to do is to go and pass the exam.
Until Next Time,
Cornelius Fichtner, PMP, CSM
President, OSP International LLC
