Part A: What proportion of dolphins in the sample have arsenic levels classified by the marine biologist as unhealthy? (4 points)

Part B: The mean aresenic level of the 28 dolphins in the sample is 5.26 parts per million and the standard deviation is 1.49 parts per million. Construct and interpret a 99% confidence interval for the mean arsenic level of dolphins in the region. (6 points) (10 points)