.Let X denotes the temperature in degrees centigrade between 3 and 4 O'clock in the afternoon during the summer and Y the demand for electric power on a scale from 1 to 10, with 10 representing peak demand. The following data are obtained over a 10-day period.

(21, 4) (31, 7) (25, 5) (34, 8) (30, 7) (23, 4.5) (32, 6) (30, 6) (38, 9) (38, 9.5)

a.Find the equation for the estimated regression line.

b.Use the estimated regression line to predict the demand for electricity when the temperature hits 35 degrees centigrade.

c.An engineer at the power plant notices that the demand for electricity on a particular afternoon is 8.5. Use the estimated regression line to approximate the outdoor temperature at this time.

d.Determine whether there is a linear relationship between X and Y or not. Use correlation coefficient 'r'.