Q1. It is required to determine Reduced Level (RL) of ceiling of a room using a levelling instrument. The RL of the benchmark is 148.20 m. The reading with staff on the benchmark is 1.080 m. The reading with staff below the ceiling and held inverted is 2.150 m. The RL of the ceiling will be
- (1) 151.43 m
- (2) 149.27 m
- (3) 147.13 m
- (4) 148.21 m