The operator of an electric plant was concerned about the performance of some of its wind turbines.
He consulted the manuals to find the rotor diameter of each turbine (in meters), x. Then, on a day with steady wind, he checked the control panel and noted each turbine's power output (in kilowatts), y.
The least squares regression line of this data set is:
y= 81.517x – 3,836.145
For each additional meter of rotor diameter, the least squares regression line predicts the power output of a turbine would increase by____ kilowatts.