The following data is a subset of data obtained in an experiment to study the relationship between x = soil pH and y A1. Concentration/EC: x 4.04 4.07 4.10 4.10 4.19 4.23 4.25 4.25 4.29 4.40 4.48 4.51 4.63 4.70 4.73 4.81 11.21 0.78 0.84 0.98 0.63 0.76 0.40 0.47 0.39 0.29 0.19 0.26 0.11 0.11 0.05 0.05 A cubic model was proposed in an article, but the version of Minitab used by the author of the present text refused to include the x3 term in the model, stating that "x3 is highly correlated with other predictor variables." To remedy this x = 4.3613 was subtracted from each x value to yield x' = x-x. A cubic regression was then requested to fit the model having regression function The following computer output resulted Parameter Estimate Estimated SD 0.3335 -1.2387 2.5669 -2.8754 0.0423 0.2758 0.6618 2.5954 (a) What is the estimated regression function for the "centered" model? (Round your answers to four decimal places (x - x)2 + (x - x) (b) What is the estimated value of the coefficient 3 in the "uncentered" model with regression function y-Po + |x + 2x2 + 3x3? (Round your answer to four decimal places.) What is the estimate of 27(Round your answer to four decimal places.) (c) Using the cubic model, what value of y would you predict when soil pH is 4.2? (Round your answer to four decimal places.) Calculate the test statistic and determine the P-value. (Round your test statistic to two decimal places and your P- value to three decimal places.) p-value =