A corporation administers an aptitude test to all new sales representatives. Management is interested in the extent to which this test is able to predict sales representatives' eventual success. The accompanying table records average weekly sales and aptitude test scores for a random sample of eight representatives.
Weekly Sales: 10, 12, 28, 24, 18, 16, 15, 12
Test Scores: 55, 60, 85, 75, 80, 85, 65, 60
a) Estimate the linear regression of weekly sales on aptitude test scores.
b) Interprest the estimated slope of the regression line.