- #1

- 7

- 0

Diameter (cm)

2.125

2.090

2.065

2.240

2.110

2.100

2.080

2.240

This gives an average of 2.131 +- 0.0695

This makes the density = 9.01 g/cm^3 +- propagation of uncertainty

Trying to calculate this, I have: sqrt( ((1*0.5) / 584.9)^2 + ((-2 * 0,0695) / 2.131)^2 + ((-1 * 0.003) / 18.195)^2 ) = 0.0652

However the online grading system say's that I'm wrong. So where have I gone wrong with the uncertainty of the density. All of the other values have been graded and marked correct, so where did I mess up with the uncertainty.

I'm not really clear where the "1", "-2", or "-1" came from in the formula above, I was basing it on my notes from class.