How to create assessment by Auto selection of items

Click the Manage button of your desired course and then click the Instructor Tools button of your desired section.
Click the Assessments tab located on your dashboard and click the Create new assessment button next to the search box. Provide Name, Feedback, Duration, and settings required for the assessment.
To add items automatically, select the Auto Selection option from the drop-down and provide the number of items in the Items box. This will create assessments with random questions from exercise, test sets, labs, and assessments. Click the Save button to freeze your preferences.