A line of differential level is run from benchmark Oak (elevation 753.01) to station 1300 on a proposed alignment. It continued along the alignment to 1900. Rod readings were taken on stakes at each full station. The circuit then closed on benchmark Bridge, which has an elevation of 772.52 ft. The elevation differences observed are, in order, -3.03, 4.10, 4.03, 7.92, 7.99,-6.00, -6.02, and 2.98 ft. A third tie between benchmark Rock (elevation of 772.39 ft) and station 1600 is observed as 6.34 ft. What are:

(a) the most probable values for the adjusted elevations?

(b) the reference standard deviation for the adjustment?

(c) the adjusted observations and their residuals?