Average based of single select options

[shannon]

Hi! I need help creating a formula and not sure if it is possible. 

I have a table that has several tasks with a single select option of completed, missing, or n/a. I want to get the average score of the tasks that are marked as completed. 

Example: Task 1 is completed, task 2 is missing, task 3 is completed, and task 4 is completed. The average would be 75%. Or if Task 1 is completed, task 2 is missing, task 3 is missing, and task 4 is N/A. The average would be 25% and so on.  

[TheTimeSavingCo]

I think you'll need to link them all to a single record on another table and use Count fields to get the numbers, and finally a formula field to get your percentage:

Link to base