An ecological group suspects tuna are consuming dangerous levels of copper in a region of the world. Dangerous levels of copper are classified when they reach beyond 5.7 parts per million. A random sample of 21 tunas in the region were tested and the data is shown in the stemplot. (Image below) Key: 2|0 = 2.0 parts per million

Part A: What proportion of the tuna in the sample have dangerous levels of copper in their systems? (4 points)

Part B: Construct and interpret a 98% confidence interval for the mean copper levels of the tuna if the sample of 21 tuna has a mean copper level of 4.77 parts per million and standard deviation of 1.16 parts per million. (6 points)