Calculate mean from cell array from every nth value

I have a cell array of 8401x11 and in the first line are the column headings. I want skip the first 15 lines after the headings and then calculate the average of every 24th cell in column 6 and 9.

Answer 1

[Image Analyst]

Make it easy for us and attach some sample data, for example by attaching a .mat file with the paper clip icon.

Some untested code is:

ca = originalCellArray(16:24:end, [6,9])
columnMeans = mean(cell2mat(ca));