Past exam of the physics course of the year 1 of the natural sciences course of the University of Cambridge / 2011 / Paper 1 / Section A / A6 / Solution

The central estimate is $c=4.15/1.93-1=1.15026$. With independent input standard errors, the ratio-minus-one uncertainty from first-order uncertainty propagation isThe four independent reported results cluster near1.21, within about one quoted standard error of this estimate, so they are consistent at this precision. Their tight clustering is not evidence that this measurement has the same precision. If the measurements of a and b were correlated, a covariance term $-2a\mathrm{Cov}(a,b)/b^3$ would be needed. ^[ref]