Sum Values over 30 minutes for Irregular Time Intervals

[FB2015]

Hello,

I have some data that has been recording values every 3 minutes. However due to computer error some of the recordings are taken every 2,4 or even 20 minutes in some cases. The vast majority however are taken over 3 minutes.

What I would like to acheive is to be able to record and sum the value for every 30 minutes.

Is there a formula or any other way I would be able to do this for large datasets?

Please see a snapshot of the data below.

Any help is much appreciated.

Cheers

Charlie

Date	Time between reading	Minutes	Value
17/12/14			0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:03:00	3	0
17/12/14	00:04:00	4	0

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[FB2015]

Hi again,

Just realised the values were pasted as all 0.

These values obviously do range but if you could input your own it would be much appreciated.

Sorry for the rookie mistake.

Cheers

Charlie