I need help writing a macro that will divide a 5000 row table into
groups of 30 rows, and find the average of each group?

I've got a data table with blood pressure readings taken at 1-second
intervals. I need help writing a macro that will take the table,
divide the data into groups of 30 rows and spit out the average of
certain columns in each group (I need one column for systolic,
diastolic, MAP, etc., however, the table contains columns of
irrelevant data), which will in effect give me averages other 30-
second intervals.

To make things more complex, the actual readings start at row 48.

this is an excel spreadsheet basically...just raw numbers in a
spreadsheet.

to be more specific, there are exactly 5120 rows in the spreadsheet
and 26 columns. I need to divide the 5120 rows into groups of 30 rows,
and for each group, find the average of columns B,G,H,and I.