When you create an activity you have the option to have it consist of a randomised set of pages/questions, imported from your Content Bank.
Follow these steps:
1. Create a new activity
2. Choose "Add question from Content Bank":
3. Choose "Rule based" at the upper right corner
4. Define your parameters for the questions you want to add
Note: You can see the number of available pages from your content bank according to your present search parameters at the bottom left.
5. Press "Generate" at the bottom.
6. When you are satisfied with your pool of question to the right you can press "Import" at the lower right corner. The questions will be imported to your activity.