In: Statistics and Probability
A manufacturer bonds a plastic coating to a metal surface. A random sample of nine observations on the thickness of this coating is taken from a week's output and the thickness (in millimeters) of these observations are shown below. Assuming normality, find a 90% confidence interval for the population variance.
19.1.
21.7
18.7
20.1
21.5
19.5
19.1
20.2
20.3