How can I calculate rate (events per minute) in Google Sheets?

Question

I am working on creating a spreadsheet template for a video observation tool that my organization will use. Specifically, we will watch ~20-minute long videos, and record the rate (occurrences per minute) of certain behaviors within subsections of the video. For example, "in the clip from 2:06 to 4:30, the speaker asked the audience an average of 2.5 questions per minute."

I think it would be easiest for users to denote individual clips by providing start and end times (eg Start: 22:40 End: 23:02). Users should be able to input a count of certain occurrences, and then the spreadsheet will divide that number by the time elapsed and calculate a rate per minute. That is to say, if the speaker asked 8 questions between the timestamps 22:40 and 24:20, the spreadsheet should return a value of 8/(1.67 minutes) = 4.8 questions per minute.

I'm having trouble figuring out a way to enter time values in Google Sheets without it treating them as actual times in a 24-hour day. For example, 22:40 shouldn't refer to 00:22:40am nor to 10:40pm; I just mean 22 minutes and 40 seconds. I guess in theory, I would need it to treat the End Time as x-many minutes (or fractions of a minute) after a given Start Time, so it would need to calculate the total number of seconds elapsed between two mm:ss values and divide that sum by 60 to get the time elapsed in minutes. Then, I could simply divide the count of occurrences (eg 8 questions) by that number (1.67 minutes), and get my answer.

Does anyone have any tips about how this could be done? Thank you so much for your help!!

Current State:

Start Time: 22:40 End Time: 24:20 Questions Asked: 8

When I enter =8/(End Time - Start Time), I get 0:00 for some reason. I want it to return 4.8.

Answer 1

Format those durations as Format > Number > Duration . Enter durations complete with elapsed hours, minutes and seconds, as in 0:22:40 and 0:24:20 .

You can then calculate events per minute like this:

=E2 / 24 / 60 / (T2 - S2)

...where E2 is the total number of events, S2 is the start moment, and T2 is the end moment.

Format the formula cell as Format > Number > Number .

See this answer for an explanation of how date and time values work in spreadsheets.