I am trying to build a formula that will add the values from another column and identify everytime the value equals 3483 to identify intervals.

Example:
IntervalStart SumOfCallsAnswered
00:00:00 159
00:30:00 108
01:00:00 109
01:30:00 74
02:00:00 60
02:30:00 49
03:00:00 68
03:30:00 24
04:00:00 31
04:30:00 29
05:00:00 46
05:30:00 40
06:00:00 136
06:30:00 217
07:00:00 255
07:30:00 401
08:00:00 747
08:30:00 914
09:00:00 1,149
09:30:00 1,074
10:00:00 1,253
10:30:00 1,214
11:00:00 1,370
11:30:00 1,480
12:00:00 1,506

I have 1500 lines of rows of data like this and I am looking for a way to standardize it in a formula.

Hoping someone can help.