Making auto parts A grinding machine in an auto
parts plant prepares axles with a target diameter
p = 40.125 millimeters (mm). The machine has
some variability, so the standard cleviation of tlic
diameters is a = 0.002 mm. The machine operator
inspects a random sample of 4 uxles cach hour for
quality control purposcs and records llic sample
mcan diameter 1. Assuming that the process is work-
ing properly, what are the mean and standard devia I
fion of the sampling distribution of ? Explain.