An educator is interested in exploring how a short refresher course covering correlated- and independent-samples t tests would affect students' knowledge and skills in preparation before a major examination. Fifteen randomly selected students completed a pretest before taking the refresher course. Two days following the refresher course, all fifteen students completed a posttest. Use α = .05two-tail to determine whether there was a significant change in scores. The data are contained in the PDF found in this folder. What is the value of tobt? Hint: This value should be between 2.90 and 3.00.