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

Observation 1 2 3 4 5 6

A 792.8 791.8 792.4 792.6 791.1 791.6

B 791.2 792.0 788.2 788.7 794.3 793.4

(a) Why are these matched-pairs data?

A.

Two measurements (A and B) are taken on the same round.

B.

The measurements (A and B) are taken by the same instrument.

C.

All the measurements came from rounds fired from the same gun.

D.

The same round was fired in every trial.

(b) Is there a difference in the measurement of the muzzle velocity between device A and device B at the =0.01 level of significance? Note: A normal probability plot and boxplot of the data indicate that the differences are approximately normally distributed with no outliers. What is your conclusion regarding Upper H0?

Do not reject H0.

RejectReject Upper H0.

(c) Construct a 99% confidence interval about the population mean difference. Interpret your results.