In a regression model predicting sales based on advertising, what can be inferred if the regression line is y=500+35x with a coefficient of determination of .90?

The regression line provided, expressed as ( y = 500 + 35x ), indicates the relationship between sales (y) and advertising spending (x). The slope of the line, which is 35, tells us that for each unit increase in advertising, sales are expected to increase by 35 units. Since this slope is positive, it signifies a positive relationship between sales and advertising.

Additionally, the coefficient of determination, which is .90, indicates that 90% of the variance in sales can be explained by the changes in advertising. This high value suggests a strong positive correlation. A high coefficient suggests that as advertising increases, sales also tend to increase significantly, further supporting that the relationship between sales and advertising spending is indeed positive.

Thus, the correct inference is that there is a positive correlation between sales and advertising, reinforcing the conclusion drawn from the model's slope.