How do I calculate averages from experimental data?

[Astro]

The attachment contains the data, calculations, and my question at the end in italics.

I have posted my question in the physics category because it is my only point of reference for a question of this type. In other words, I believe physics are best suited to answering my question.

I would be grateful for any help.

Thanks.

 

[Astro]

I posted the same question in the math thread and the problem's been solved. Anyone interested follow this link: https://www.physicsforums.com/showthread.php?p=1161895#post1161895