Answer Happy

Please answer the second question
Suppose a second gauge block of length L2 is compared with the same calibrated gauge block using the same length comparator. Assuming the measured differences are statistically independent, derive an expression for the 2 x 2 covariance matrix Vi associated with the estimates I = (11, 12) of the lengths L = (L1,L2)T. (35%] Use Vi derived in (d) to evaluate the standard uncertainties u(lı + lz) associated with the estimates lı + l2 of the sum L1 + L2 of the lengths.