Yes, you can do this on the assignments screen.
Select the Box next to the Enable Random Selection at the bottom of the Applicant listing and enter the number of applicants you want to be assigned randomly in the blank select field next to the Go, and click Go. Do the same for the Committee listing.
The system will then automatically check that number of applicants and/or check that number of committee members.
Click the Save Assignments to save that selection. Repeat for each batch.