The PCB concentration of a fish caught in Lake Michigan was measured by a technique that is known to result in an error of measurement that is normally distributed with a standard deviation of .08 ppm (parts per million). Suppose the results of 10 independent measurements of this fish are
11.2, 12.4, 10.8, 11.6, 12.5, 10.1, 11.0, 12.2, 12.4, 10.6
(a) Give a 95 percent confidence interval for the PCB level of this fish.
(b) Give a 95 percent lower confidence interval.
(c) Give a 95 percent upper confidence interval.