The precision of equipment and instruments is measured by the variability of their operation under repeated conditions. The output from an automatic lathe producing the diameter (in millimeters) of a part gave the following readings for a random sample of size 10:
A. Find a 90% confidence interval for the variance of the diameters.
B. Find a 90% confidence interval for the standard deviation of the diameters.
C. Test the null hypothesis that the variance of the diameters does not exceed 0.05 mm2. Use a significance level of 0.10.
D. Does the mean setting for the machine need adjustment? Is it significantly different from 9.5 mm? Test at a significance level of 0.10.