A researcher is interested in the relationship between hourly earnings and years of education. Data was collected from 100 individuals. Average hourly earnings are $20 per hour with a standard deviation of $6 per hour. Average years of education are 15 years with a standard deviation of 4 years. The correlation between the two variables is 0.4. Hourly earnings are regressed on years of education. What is the slope of the OLS regression line?