Here's the question: The PCB concentration of a fis hcaught 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. 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 Give a 95 percent interval for the PCB level of this fish. -------- So, I have a small sample size (10) and a normal distribution. I attempted to use the t-table for this solution but the solutions manual used the Z-distribution table. I can't figure out why.