SQL Challenge

Ok, I have to create a table based off of two tables. On of them is an archive and one of them has user names. The archive holds all the information inputed by the user and to audit them we want to be able to randomly check 10% of their work for each individual. So, for example, Employee Linda works 100 tickets on one given day. We want to be able to review 10 of her tickets to somewhat have a check to see if she is doing her work correctly. I appreciate any ideas from anyone who would like to help out.