Calculate duration based on a critera of another column

[greendaffodil]

Hi everyone,

I'm having trouble with making a correct excel formula.
My data exists of two columns, one column with date and time and another column with either a '0' (not present) or a '1' (not present).
What I want to do is calculate the duration of the absences through time.

So, for example:

21-05-11 11:23 1
21-05-11 11:38 0
21-05-11 11:53 1
21-05-11 12:08 0
21-05-11 12:23 0
21-05-11 12:38 1

The first absence lasts 15 minutes and the second absence lasts 30 minutes. I'm wondering if there is a formula which could provide that automatically?
Hopefully someone can help me out.

Greetings,
Daphne

[zbor]

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