Final answer:
The slope of the given regression line ŷ = 1.7x + 2.1 is 1.7, indicating a 1.7-unit change in the predicted variable for each one-unit increase in x.
Step-by-step explanation:
The slope of the regression line is the coefficient of the independent variable x in the equation ŷ = mx + b. In the given regression equation ŷ = 1.7x + 2.1, the slope is 1.7. This represents the rate at which ŷ, the predicted variable, changes for every single unit increase in the independent variable x. Therefore, for this regression line, there is an increase of 1.7 in the dependent variable (ŷ) for every one-unit increase in x.