The graph at the left is a scatter plot with 40 points, each representing the temperature of the ocean water, measured at a fixed location off the coast of West Iceland, and the air temperature, measured on land at a fixed location in West Iceland. Both the water temperature and the air temperature, in degrees Celsius, were measured at noon on Wednesday of each of 40 consecutive weeks last year. The solid line is the regression line and the dashed line is the line through the points (0,0) and (6,6).
The relationship between the water temperature and the air temperature is .
The slope of the regression line is the slope of the dashed line.