Okay I'm doing a lab report, and I need to find the average of two trials. Can someone show me step-by-step how do find the uncertainty for this average:

(4.32g+4.17g)/2
=4.25

The values I used and their uncertainties:
4.32g +/- 0.02
4.17g +/- 0.02

To find the uncertainty for the average of two trials, you need to consider the uncertainties of each individual measurement. You can calculate the uncertainty of the average using the following steps:

1. Take the absolute difference between the two measurements:
|4.32g - 4.17g| = 0.15g

2. Divide this absolute difference by two (since you are calculating the average):
0.15g / 2 = 0.075g

3. Add the uncertainties of each individual measurement:
0.02g + 0.02g = 0.04g

4. Take the larger value between the divided absolute difference and the sum of the uncertainties:
0.075g > 0.04g, so you choose 0.075g.

Therefore, the uncertainty for the average is 0.075g.
In the case of your example, the average is 4.25g with an uncertainty of +/- 0.075g.