Question

2. A distance was measured by pacing as 267 ft with a standard deviation of ±3 ft. It was then measured as 268.94 ft with a steel tape and had a standard deviation of ±0.05 ft. Finally, it was measured as 268.99 ft with an EDM. The EDM instrument and reflector setup standard deviations were ±0.003 ft and ±0.005 ft, respectively, and the manufacturer’s estimated standard deviation for the EDM instrument is ±(2 mm + 2 ppm). What is the most probable value for the distance and the standard deviation of the weighted mean?

Answer 1