1. The problem statement, all variables and given/known data an experiment is performed to test whether the displacement D produced on a piezoelectric drive behaved linearly with the potential voltage V applied across it. The following data are obtained: V (volts) D (um) 0.1 50 0.2 101 0.3 151 0.4 198 0.5 249 0.6 298 0.7 346 0.8 393 0.9 438 1 181 1.1 521 the uncertainty on the voltage setting can be considered negligible. While the displacement measurements are performed with a linear encoder with an uncertainty of +-5um calculate the chi-squared probability for the fit 3. The attempt at a solution when I plotted the graph the equation Excel displayed was: y=474.82x+8.3818 I have thought about two possibilities: when calculating chi-squared, the values of V(subscript theory) be taken by using the equation on the least-squared-fitted graph on Excel? y=474.82x+8.3818 or does one assume that V is supposed to be proportional to D and that the graph is meant to go through the origin? Should I use the above equation to work out what Dis supposed to be in theory when working out chi-squared? or should I assume it's supposed to go through the origin?