(12 points) The national average for the 7th grade aptitude test in 2004 was 85. The principal at O'Farrell Middle School feels that the average for his students this year will be different. He randomly selected 10 students to take the aptitude test.

Their scores were: 83.4 72.1 89.2 86.2 83.3 85.9 79.2 80.3 88.5 90.1

A. (4 points) State the sample mean and mean and sample standard deviation. Use the appropriate notation.

B. (6 points) Determine a 95% confidence interval

B. (2 points) Does this confidence interval suggest that the average score of 85 is different today than 2004? Explain.