G by free fall experimental error

[Darth Frodo]

This isn't so much a H/W question, but we have 2 sets of values,

TMax and Tmin.

Δ is the difference between them.

We are told to get Δ/2 and get the %uncertainty of this.

Why do we halve Δ?

 

[Nessdude14]

If you choose a value right in the middle of your max and min values, then you can say that the max value differs by Δ/2, and the min also differs by Δ/2. So Δ/2 could be considered sort of a maximum error value.