Estimate a quadratic regression model where the GPA of middle school children is regressed on hours and hours-squared. (Negative values should be indicated by a minus sign. Round your answers to 2 decimal places.) GPAˆ = + Hours + Hours2 b. Is the quadratic term in this model justified? multiple choice Yes, based on the R2. Yes, based on the significance of Hours2. No, based on the R2. No, based on the insignificance of Hours2. c. Find the optimal number of weekly hours of TV for middle school children. (Round coefficient estimates to at least 4 decimal places and final answer to 2 decimal places.)