Dolphins are suspected to be consuming dangerous levels of arsenic. Dangerous levels of arsenic are classified when they reach beyond 7.0 parts per million. A random sample of 28 dolphins in the region were tested and the data is shown in the stemplot.

2|4 = 2.4 parts per million

:What proportion of the dolphins in the sample have dangerous levels of arsenic in their systems? (4 points)

:Construct and interpret a 99% confidence interval for the mean arsenic levels of the dolphins if the sample of 28 dolphins has a mean arsenic level of 5.26 parts per million and standard deviation of 1.49 parts per million. (6 points)