ASK YOUR TEACHER PRACTICE AN Public health and safety officials have classified the Zika virus as a hazardous threat to pregnant women in Brazil. A study based in Rio found the virus to be more active near a body of water that was found to be polluted. A study of 20 water samples found an aver chemical waste of 207 g per mile with a standard deviation of 10.55 g. LO USE SALT (a) What are the degrees of freedom for this study? (b) Find the 95% confidence interval (in g per mile) for this study. (Use a table or technology. Round your answers to three decimal places.) g per mile (c) What would happen to the margin of error if the sample size increased? O It would also increase. O It would decrease. It would stay the same. It would go to zero. (d) What would happen to the margin of error if the confidence level increased? It would also increase. O It would decrease. It would stay the same. It would