As given reading = 1.55, 2.74, 0.75, 1.79 length of staff = 3.0m first reading = 1.155 = Back sight Second reading = 2.74m and third reading = 0.75m ∵ [0.75 < 2.74 < 3] maximum length is 3m So, second reading is fore sight. Third after shifting Inst (dump level). First reading is Back sight. Second is : FS Third is → B.S and last is → FS. Hence, the correct order is BS, FS, BS, FS.