Calculate average workdays it takes for certain requests to be complete.
Will preface this by stating I have to reference another sheet that I do not have the ability to edit that sheet's information. I'm working off a sheet I created as a formulate reference sheet used for a dashboard. So when creating calculations I have to use formulas that reference the other sheet with the request information.
I have a Sheet that tracks different requests. One type of these requests we'll call "Fast Service." Anytime a new "Fast Service" request is opened on a row the Request Opened column generates the date it is opened. When the request is complete, the Completed Column generates a date. I would like to calculate the average number of workdays it takes for all "Fast Service" requests to be completed on an ongoing basis that I can use in my dashboard. I'm not sure how to do this using a reference sheet and two date columns. Any help would be greatly appreciated.