Getting a random problem set each time for a single test

QUESTION
Is it possible to make a bank of questions? For example I have 40 questions in the bank but the test is only 20 questions.

ANSWER
Yes, you can make a bank of questions of which you only use half.  Create a test with 40 questions.  After creating the test, click on the test name to edit the test.  In the Length setting, choose 20 / 40, and each time a random set of 20 questions will be chosen for the student, out of the whole problem set.