In the leveling network of Figure 10.1, recall that the lengths of lines 1, 2, and 3 were 2, 3, and 4 miles, respectively. If the observed elevation differences in lines 1, 2 and 3 were +21.20 ft, +21.23 ft and +21.29 ft, respectively, find the weighted mean for the elevation difference, and the adjusted elevation of BMX (Note: All level lines were run from BMA to BMX.)