From the data on CAT scans in Exercise 8-45
(a) Find a two-sided 95% confidence interval for the standard
deviation.
(b) What should you do to address any reservations about the
confidence interval you found in part (a)?

A healthcare provider monitors the number of CAT
scans performed each month in each of its clinics. The most
recent year of data for a particular clinic follows (the reported
variable is the number of CAT scans each month expressed
as the number of CAT scans per thousand members of the
health plan):
2.31, 2.09, 2.36, 1.95, 1.98, 2.25, 2.16, 2.07, 1.88, 1.94, 1.97,
2.02.