Acertain test preparation course is designed to 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 6 students' scores on the exam after completing the course: 8,6,12,15,42,23 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. step 4 of 4 : construct the 80% confidence interval. round your answer to one decimal place.