A Google AdWords Help thread asks what do you need to score in order to pass the Google AdWords Professional exam?
There are two exams:
(1) Google Advertising Professionals Exam (2) Fundamentals and Search Exam
The first one, the Google Advertising Professionals exam needs an 85% score to pass. Whereas the second one, the Fundamentals and Search exam needs an 80% to pass.
AdWordsPro Sarah explained in the thread:
I checked with the people in charge of the Google Advertising Professionals Exam and it looks as if the passing score for the Fundamentals and Search exams are 85% and 80% respectively.
She then added that Google will adding more practice quizzes about the April or May time.
Forum discussion at Google AdWords Help.