How to apply a 30 second moving average to data with inconsistent time intervals

Hello,

Many thanks in advance to all those who use this site as it has saved me so much time in the past!

My current problem hopefully has a simple answer but is currently beyond my excel level. I am using Excel 2010 and wish to create a column that produces a MOVING 30 SECOND AVERAGE. My issue is that my time data (in seconds) is not consistently spaced (e.g. 2, 5, 6, 7, 10 etc) and therefore cannot apply an average over a constant number of cells. I will try to include an example data sheet so hopefully that will make things clearer where I have been vague.

Many thanks for your help,

Andy

Hi.
I am not sure
=SUM(OFFSET(B3,0,0,MATCH(A3+30,A3:A119,1),1))/COUNT(OFFSET(B3,0,0,MATCH(A3+30,A3:A119,1),1))