To estimate the benefits of an SAT prep course, a random sample of 10 students enrolled in the course is selected. For each of these students, their entrance score on the exam taken at the beginning of the course is recorded. Their exit score on the exam they take at the end of the course is recorded as well. The table displays the scores. A 3-column table with 10 rows. Column 1 is labeled student with entries 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Column 2 is labeled Before with entries 800, 870, 860, 820, 1140, 1050, 850, 910, 830, 1140. Column 3 is labeled after with entries 1100, 1010, 1000, 980, 1410, 1270, 1020, 1010, 1060, 1340. What is the mean difference (after - before) and the standard deviation of the differences? x Overbar difference = 185, s difference = 59.506 x Overbar difference = 185, s difference = 62.725 x Overbar difference = 193, s difference = 59.506 x Overbar difference = 193, s difference = 62.725