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 have measured the calcium concentration from a random sample of 18 locations in the river and calculated a mean of 97.4 mg/L, with a standard deviation of 4.1 mg/L. The fish are able to tolerate calcium concentrations up to 95 mg/L. a. Assuming a normal distribution, calculate a 95% confidence interval for the mean calcium concentration in the river. b. Do your data suggest that the fish are being negatively impacted? Explain your answer. c. Assuming that you held everything else constant, how would the width of the confidence interval change if you doubled your sample size from 18 to 36? Would it become wider, narrower, or stay the same?