50% is the pass rate?

Not exactly, you are only partially correct.

Everyone that takes the exam will get 50% correct and 50% wrong. The exam is what we call a CAT exam, meaning that questions are given to you based on how you answered the previous question. There is no exam already in place that you are going to be given, it will all depend on you.

Next, each and every question has a rating given to it. You must get the majority of your questions that you pass over the passing standard level. So one can easily get 50% correct and not pass the exam. It is the level of the questions that you get and how you do with those of the higher level that will determine your passing.

Best of luck to you.