The sheet attached is purely an example of 20 made up people. The number I wrote above is just what I'd like the output to look like not real numbers.

So each half an hour interval would just count if they were present or not. For example, 10:15 - 15:45, would be a yes to 10:00 and 15:30 (and all times between) but would not be counted for 10:00 and 16:00.

Does this make sense?