A vortex flowmeter is tested by applying a constant flow rate of 100 litres/min to it,
measured by an accurate, calibrated, reference positive displacement meter. A set of
12 measurements is made as a reference set of measurements to assess the standard
deviation and standard error of the mean for measurements made by the device. The
measurements obtained for this reference set are given as:
99.8, 99.3 100.2, 99.7 100.9, 99.9, 99.4 101.1, 99.5 100.8 100.4, 99.0
When the vortex flowmeter is subsequently used in a workplace to measure the flow
rate of liquid through a pipe, a reading of 94.6 litres/min is obtained. What is the
likely error in this measurement, expressed as a 95.4% confidence limit?