Staff readings on pegs x and y from X station are 1.755 m and 2.850 m, and from station Y on staff head at Y and X are 0.655 m and 1.560 m. If reduced level of X is 105.5 m, the reduced level of Y is

ANS:B - 104.5 m

RL of Y = RL of X + back sight of Y - foresight of Y.

105.5+0.655 - 1.560 = 104.595. RL of point x + backsight x = height of instrument (105.5 + 1.755 = 107.255).

RL of y = height of instrument - fore sight of y (107.255 - 2.850 = 104.405). By using the formula of reciprocal levelling find the value of h and then we know then.

RL of pt B = RL of pt A - h.