The accompanying data were compiled by the admissions office at a college during the past 5 years. The data relate the number of college brochures and follow-up letters (x) sent to a preselected list of high school juniors who had taken the PSAT and the number of completed applications (y) received from these students (both measured in units of a thousand). x 4 4.5 5 5.5 6 y 0.5 0.6 0.8 0.9 1.2 (a) Determine the equation of the least-squares line for these data.