Reciprocal levelling was conducted across a wide river to determine the difference in level of point A and B, A situated on one bank of the river and B situated on the other. The following results on the staff held vertically at A and B from level stations 1 and 2, respectively, were obtained. The level station 1 was near to A and station 2 was near to B.
|
Instrument at |
Staff reading on |
|
|
A |
B |
|
|
A |
1.485 |
1.725 |
|
B |
1.190 |
1.415 |
If the reduced level of B is 55.18 m above the datum, what is the reduced level of A?
1
54.574 m
2
54.883 m
3
55.413 m
4
55.786 m