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 3 students' scores on the exam after completing the course:

6,11,18

Using these data, construct a 90% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal.

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Step4of4:

Construct the 90% confidence interval. Round your answer to one decimal place.