Answer: The viscosity (y) of an oil was measured by a cone

Chapter 13, Problem 13.28

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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 estimated regression function resulting from the n 6 observations was y 113.0937 3.3684x .01780x2 a. Estimate Y75, the expected viscosity when speed is 75 rpm. b. What viscosity would you predict for a cone speed of 60 rpm? c. If y2 i 8386.43, yi 210.70, xiyi 17,002.00, and x 2 i yi 1,419,780, compute SSE [y2 i 0yi 1xiyi 2x2 i yi], s2 , and s. d. From part (c), SST 8386.43 (210.70)2 /6 987.35. Using SSE computed in part (c), what is the computed value of R2 ? e. If the estimated standard deviation of 2 is s 2 .00226, test H0: 2 0 versus Ha: 2 0 at level .01, and interpret the result.