A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at the beginning and end of the course to determine the effectiveness of the course. The following measurements are the net change in 4 students' scores on the exam after completing the course:

12,7,13,11

Using these data, construct a 80% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal.

Copy Data

Step 1 of 4:

Calculate the sample mean for the given sample data. Round your answer to one decimal place.

Step 2 of 4:

Calculate the sample standard deviation for the given sample data. Round your answer to one decimal place.

Step 3 of 4:

Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

Step 4 of 4:

Construct the 80% confidence interval. Round your answer to one decimal place.