Help
I need help.
I need the average between 8:00 AM - 8:15 A.M., 8:15 A.M. - 8:30 A.M. and so on in 15 Min intervals
Can someone please help me build a formula to compute and avg. between those times please. ty

A B C D E
1 Seconds Times between and Answere avg.
2 150 8:11:59 8:00 AM 8:15 AM 275
3 400 8:09:40 8:15 AM 8:30 AM 400
4 200 8:18:01
5 600 8:30:00