An investigator studying the effects of stress on blood pressure subjected mine monkeys to increasing levels of electric shock as they attempted to obtain food from a feeder. At the end of a 2-minute stress period, blood pressure was measured. (Initially, the blood pressure readings of the nine monkeys were essentially the same).

Blood Pressure Shock Intensity Y X 125 30 130 30 120 30 150 50 145 50 160 50 175 70 180 70 180 70 Some helpful intermediate calculations: X = 450, Y = 1365, X2 = 24900, Y2 = 211475, (X)2 = 202500, (Y)2 = 1863225, X Y = 71450, and (X)(Y) = 614250. Using this information,

a. Plot the scatter diagram.

b. Determine the regression line relating blood pressure to intensity of shock.

c. Place a 95% confidence interval on the slope parameter .

d. Test the null hypothesis of no linear relationship between blood pressure and shock intensity (stress level). (Use  = 0.01.)

e. For a shock intensity level of 60, what is the predicted blood pressure?