I am not certified to the ASQ CBA, but my experience with several of their other certifications has been that if your study material (e.g. QCI primer) covers the scope of the Body of Knowledge you shouldn't feel that you are missing much. Primers will not contain the text of standards or reference documents (such as from the FDA or GHTF) so you may want to supplement your study materials with those freely available sources. Keep in mind that the BoK also calls out what level of cognition the exam is expecting you to have for each area of the BoK.
As with many other ASQ certifications, it appears that the CBA leans heavily on Auditing (45 questions) and QMS (50) and general Quality Tools (15) with only 25 questions focused on the specific technical area. This doesn't mean you can fail most of the technical questions and be certified, I only point out which areas will contain the most questions. If you have other ASQ certifications certain areas will be familiar to you.
Sidebar: The ASQ question banks are created by volunteers who are given some basic amount of training in how to write questions at the required level of cognition, with the additional requirement (at least at the time of my most recent participation in one of the more technical areas) that "Primers" could not be used as the source of knowledge for any given question; all questions had to have one or more primary sources. The question bank contents are subjected to some round-robin evaluation, so I can say that 'your mileage may vary' when it comes to the wording of the questions as well as if they hit the appropriate level of cognition. It has been my experience that less experience question-bank writers lean too heavily on the remember/knowledge level, this bias occasionally shows up in the certification exams. Another peculiarity that I have seen is that the forced reliance on non-survey primary sources if that occasionally (usually 1 question per exam) there will be a question worded in a very specific way that is unique to one (primary source) author's area of specific expertise.
Tinge, I really appreciate your feedback.
You mentioned about the quantity of questions in the test. Do you know how many questions I need to answer correctly to pass or what is the % in each section Do I need to have to pass?
Iam really worried since auditor is a Requirement for my current role, so this test is very important to me.
The exact percentages are never revealed, and as far as I know they are not established in advance. There are several reasons for this, one is that there may be a particular question that is poorly worded or is ambiguous enough that a significant number of test takers do not get the 'correct answer'. This is not to say that ASQ certifies 'on a curve', rather they are open to evaluating the quality of an individual certification exam after it has had contact with the candidates.
In the event you do not pass the first time, ASQ will provide you with feedback that includes which specific areas of the BoK where you fell short. You won't be told the exact questions you got wrong. I believe you are allowed to retest within a certain amount of time with no negative consequences from ASQ.
You do not need to be perfect on any particular section, so if there is one question in a particular area of the BoK that has you stumped, don't be afraid to skip it. I haven't taken any of the certification exams since the electronic test-taking method was adopted, but when taking paper-based certification exams I would first read through all the questions (answering the ones that I felt had 'obvious' answers) to categorize them according to the BoK, and then go back and answer all of the questions within one BoK area before moving to the next. Writing only for myself: I always left the technical and/or mathematical (often statistical) questions for last, as those can sometimes require more rigor to verify the correct answer. I never ran out of time during any of the certification exams.