Consider the following sample data for the variables y and x:

x 30.3 4.8 15.2 24.9 8.6 20.1 9.3 11.2 y 14.6 27.9 17.6 15.3 19.8 13.2 25.6 19.4

a. Calculate the linear regression equation for these data.

b. Determine the predicted y value when x = 10.

c. Estimate the change in the y variable resulting from the increase in the x variable of 10 units.

d. Conduct a hypothesis test to determine if an increase of 1 unit in the x variable will result in the decrease of the average value of the y variable. Use a significance of 0.025.