Concepts: When staff is held vertically downward, then Height of instrument is HI = Reduce Level (RL) + Staff Reading (SR) Also, Reduce level of any other point on ground is calculated as: RL = HI – BS/FS {BS is Back Sight and FS is Fore Sight} Calculations: RL of Point A = 240 m HI at A = RL at A + BS at A (HI)A = 240 + 2.024 = 242.024 m (RL)TP2 = (HI)A - FS at A = 242.024 – 1.42 = 240.604 m HI when instrument is between TP1 and TP2,(HI)1−2 = RL at TP1 + BS between TP1 and TP2 (HI)1−2 = 240.604 + 1.986 = 242.59 m (RL)TP2 = (HI)1−2 - FS between TP1 and TP2 = 242.59 – 2.1 = 240.49 m ∴ The reduced level of TP2 is 240.49 m.