You should not have spent a lot of tme on ONE single question. You lost valuable time that you could have spent on other questions. These exams are not only designed to test your knowledge but more importantly are designed to test on how you manage your time and if you have a great plan of attack (strategy). I remembered one professor from college and he used to tell us that there is a strategy for doing multiple chioce exams, you just need to learn how to pick the right multiple choice answer as oppose to actually solving the whole problem. Those are two different concepts. People should spend 80% of the time on the questions that you know you can do and if time allows take an educated quess on the rest. Another tip is to scan through the exam and try to find the easy and doable problems first and do those, DO NOT start anwering the exam by going in a chronological order like 1, 2, 3 and so on, if you do you will get stuck on one question and at the end you won't have time to answer doable questions that happen to be towards the end. Out of the 55 questions and based on past scores, passing percentages, etc., you will most likely pass if you answer 32-36 correctly.