Need to cycle 32 questions in question bank for a 12 question quiz...

Hi!  I am creating a post assessment that has 12 questions.  There are 32 questions in my question bank that need to be cycled randomly for this graded assessment.  How do I set up my quiz to contain 12 graded questions and pull those questions from my question bank that contains 32 questions?  I also need to know the best way to score the quiz once it is complete.  Thanks!