The article "Ozone for Removal of Acute Toxicity from Logyard Run-off" (M. Zenaitis and S. Duff, Ozone Science and Engineering, 2002: 83-90) presents chemical analyses of runoff water from sawmills in British Columbia. Included were measurements of pH for six water specimens: 5.9, 5.0, 6.5, 5.6, 5.9, 6.5. Assuming these to be a random sample of water specimens from an approximately normal population, find a 95% confidence interval for the mean pH.