Oct 12, 2018 - 11:57 AM
You could add a Gradebook Rule that would adjust the lowest grade to a specific value. The Gradebook Rule tab is located in Gradebook/Manage. See this snapshot below. It may not appear very large in this reply, but the documentation links will provide a better view these fields.
See the following documentaton: Gradebook Rules
See the following video: Gradebook Rule Video
Best Regards - Aeries Support