I am trying to figure out the correct way to average the number trips and spend by customers in a certain mileage radius over a 3 month period, and then populate those totals into specific segmented "spend" categories. My confusion is with the proper way to generate the correct average. Do I summarize the data for each month first, then divide by the number of months, or do I just average the entire data base.

Attached is a sample of what I am trying to do. The yellow fields would be populated with the average for each category from the entire data set.

Thanks in advance.
Test Avg.xlsx