Question

Which is the arithmetic check for the height of instrument method?

(a) ∑FS + ∑BS = First RL + Last RL@

(b) ∑BS – ∑FS = Last RL – First RL@

(c) ∑FS + ∑BS = Last RL + First RL@

(d) ∑BS – ∑FS = First RL – Last RL@

I got this question in final exam.

This is a very interesting question from Methods of Levelling topic in division Basic Surveying of Basic Civil Engineering

Answer 1

Right option is (b) ∑BS – ∑FS = Last RL – First RL@

To explain I would say: To check if the readings are written properly, an arithmetic check is done. The sum of back sight (BS) and Fore sight (FS) are subtracted. It should be equal to the difference of the last and first reduced level (RL).