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Two Pegs A and B were fixed on opposite banks of a 50 m wide river. The level was set up at A and the staff readings on Pegs A and B were observed as 1.350 m and 1.550 m, respectively. Thereafter the instrument was shifted and set up at B. The staff readings on Pegs B and A were observed as 0.750 m and 0.550 m, respectively. If the R.L. of Peg A is 100.200 m, the R.L. (in m) of Peg B is ______ .
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- 17
- 40
- 100
- 85
Correct Option: C
Thus is reciprocal levelling
| ∆h = | ||
| 2 |
| ∆h = | = 0.20 | |
| 2 |
RL at B = RL at A – ∆h = 100.200 – 0.20 = 100
