A company claims that the course they offer significantly increases the writing speed of secretaries. The following table gives the scores of eight secretaries before and after they attended this...

Extracted text: A company claims that the course they offer significantly increases the writing speed of secretaries. The following table gives the scores of eight secretaries before and after they attended this course. Before 81 75 89 91 65 70 90 69 After 97 72 93 110 78 69 115 | 75 Make a 90 % confidence interval for the mean Hx – Hy of the population paired differences, where a paired differences is equal to the score before attending the course minus the score after attending the course.