Remember that even though the PMP Exam is largely based on the PMI's PMBOK Guide you should not only know all of the concepts from here, but you must be able to analyze and answer the situational exam questions with a combination of practical project management knowledge and with what the PMBOK Guide says. Generally speaking, going against PMI principles is never a good option. At least not during the PMP Exam. It is also better to choose the ethical option even though they may seem to be the tougher choice.
Here is what to expect on the exam: The PMP Certification Exam consists of 200 Multiple Choice Questions, which must be answered within 4 hours. These questions are randomly generated from a question database which has many hundred questions. Out of 200 questions answered, 25 questions are pre-test questions which will not be used for scoring. These pre-test questions are randomly inserted by the computer into your exam with the idea of evaluating whether these will be used as "real" questions in future exams. This is a normal and valid way to test new questions on actual exam takers and see how they respond. But because you don't know which ones are the pre-test questions it is important to answer all the 200 questions to the best of your ability.
Since 25 out of 200 questions are not used for scoring, effectively, 175 questions are used for scoring on the exam. However, PMI does not release a "passing score", so we don't know how many questions must be answered correctly in order to pass. After the exam you will be given an examination report on which you can see the areas where you were Proficient, Moderately Proficient and Below Proficient. It also tells you whether you passed or failed.
So the problem is this: If we don't know how many questions you have to answer correctly in order to pass the exam, how can you prepare? My recommendation is that you answer as many sample questions as you possibly can before you take the exam and gain your confidence. Only by taking many mock exams can you raise your understanding. By doing this you will come to a point where you will feel ready and know that you are ready. This is the point where your studies and practice exams will have given you the level of understanding and confidence and you will answer all PMP Certification Exam questions correctly by applying both your practical experience from being a PM and the theoretical know how from reading the PMBOK Guide.