Grouping times by 15 minute intervals

Hi All

I was wondering if someone can help me with the following:

I have a load of data which has an individual time stamp in hr:mm:ss as below.


00:21:15
03:47:36
05:56:17
06:16:41
06:31:16
06:37:44
06:57:20
08:06:45
08:31:07
08:48:29
11:08:50
12:25:00
12:25:57
14:09:22
15:02:34


I would like to categorise them into 15 minute intervals so I can then calculate the number of times something occurs in a particular 15 minute period.

For example if I would like to know how many occurances do I get between 00:00:01 and 00:15:00, 00:15:01 and 00:30:00, 00:30:01 and 00:45:00 etc

I would like to do this for the whole 24 hour clock

Output to look something like this

00:00 53
00:15 51
00:30 50
00:45 39
01:00 46
01:15 46
01:30 44
01:45 38
etc etc


I hope the above makes sense.

Thank you for your help.

You could probably do it with a Pivot Table (but I don't like those).
In the attached is a formula based method.

BSB

Thank you BadlySpelledBuoy - worked a treat!