Calculated field sum of check boxes

Hello,

I am trying to create an employee evaluation form. I'd like the calculated field to be the sum of the check boxes then divided by the total number of categories (6). Each

check box has the appropriate export value according to the rating (1, 2, 3, 4, 5).

So if an employee was rated all 5s across the 6 categories they would average out at a 5. (5 rating x 6 categories / 6 categories).

Any help on how to accomplish this would be appreciated.

Thanks in advance!