Conditional averaging

Hello again, everyone,

As I delve deeper into this project, I keep noticing things that could be improved.

Attatched is an example of the worksheet that I am working with. On the first sheet, Row 34 gives the option of "OK", "OS", or "HOLD". These options correspond to if the run in question met the criteria. At the end of each row that contains actual data, it takes the average of all of the data. What I would like to do is have only runs that are deemed OK to be included in the average. How would I need to go about doing this?