Generally, it's 70% correct to pass. However, each exam is individually evaluated on it's level of difficulty, and each question is analyzed to eliminate any outliers. You may have answered 80 questions, but you may only be graded on 78-79, and then graded on a bit of a curve (anywhere from 68-72%) depending on an array of reasons.
At the end, you will still study to get as many correct as you can. You won't study only 70% of the material or only answer 70% of the questions. And then as others have pointed out, a pass is a pass.
