This may seem like a simple question but how would I find my T^2? Is it just simply the Period (T) that we timed but squared? For example: T = 1.10s is 1.21 T^2. Or, is there some kind of formula I need to find T^2? Here is a picture of my table that will hopefully clarify:

Based off my picture above, should I plot my first coordinate at (28, 1.10) or (28, 1.21)? Or something else?

Thanks!