I've been trying to get a Google Sheets formula working for this scenario for a while now to the point I can feel Google laughing at me.

CodePudding user response：

This assumes that the dates/times in columns A & B are in a standard MM/DD/YYYY HH:MM:SS format. There may be some necessary adjustments depending on the date format you are using if it is different.

=AVERAGE(FILTER({B:B-A:A},F:F="LMM Request",A:A>=W14,A:A<=X14))