80 -50 roup of 8 students were given the same standardized test twice to see whether retaking the test affected the score. The table gives the score differences for 20 90 8 students. Use the paired t-interval procedure to determine a 90% confidence interval for the difference between the mean scores on the first test and the 60 20 90 10 ond test (retake). (Note: d = 40 and Sd = 48.99.) 90% confidence interval is from to ound to two decimal places as needed.)