The viscosity (y) of an oil was measured by a cone and plate viscometer at six different cone speeds (x). It was assumed that a quadratic regression model was appropriate, and the n = 6 estimated regression function resulting from the observations was
y = - 113.0937 + 3.3684x - .01780x²
a. Estimate µY.75, the expected viscosity when speed is 75 rpm.
b. What viscosity would you predict for a cone speed of 60 rpm?
