How do I calculate the uncertainty?

I know it should be 5% uncertainty for both the potential measured and 5% uncertainty for the potential at the surface of B which is -57.9 V.

but till I cannot do it

 

 

Now assume that there is a 5% uncertainty in the measurements for the potential (including that of VB), and then set the potential of the negative sphere to () V. Calculate the new potentials at the measured positions with their absolute uncertainties. Position (m) 0.2 0.5 1.0 1.8 2.7 3.5 3.9 4.2 Potential (V) 26.6 39.9 49.0 55.5 60.9 68.1 76.1 90.4 4.4 (the surface of sphere A) 114 Uncertainty V +1 H H It It H H H +1