The following data represent the muzzle velocity (in feet per second) of rounds red from a 155-mm gun. For each round, two measurements of the

The following data represent the muzzle velocity (in feet per second) of rounds fired from a 155-mm gun. For each round, two measurements of the velocity were recorded using two different measuring devices, with the following data obtained:

(a) Why are these matched-pairs data?
(b) Is there a difference in the measurement of the muzzle velocity between device A and device B at the α = 0.01 level of significance?
(c) Construct a 99% confidence interval about the population mean difference. Interpret your results.
(d) Draw a boxplot of the differenced data. Does this visual evidence support the results obtained in part (b)?

Observation 1 3 4 793.8 793.1 792.4 794.0 791.4 792.4 793.2 793.3 792.6 793.8 791.6 791.6 Observation 7 9 10 11 12 791.7 792.3 789.6 74.4 790.9 793.5 791.6 792.4 788.5 794.7 791.3 793.5