3. An industrial plant dumps its waste into a nearby river, but claims that it is not impacting the native fish that live in the river. You've measure the calcium concentration from a random sample of 35 locations in the river and calculated a mean of 98.2 mg/L, with a standard deviation of 3.1 mg/L. The fish are able to tolerate calcium concentrations up to 95.0 mg/L without being negatively impacted. All relevant assumptions were confirmed. a. Run the appropriate test to determine if the average calcium concentration is significantly higher than the tolerable level for the fish. Include all steps for full credit. Given: critical value = 2.03 (5pt) b. List a potential confounding variable for this study and briefly explain a possible consequence it could have on the results. (2pt)