please select all the correct answers.

4. [2pt] To test whether the slope B, in the regression model E[YIX,.XX,] = B. + B,x, + B,x, + B,x, is significantly different from 0, which of the following tests can we use? Please select ALL that apply. It's possible that there is only one correct answer. A. z-test B. t-test C. Overall F-test D. Partial F-test 5. [2pt] Consider the quadratic regression model E[Y|X = x] = B + Bx + B,x . The estimated regression equation is E[Y|X = x] = 7 - 6x + 4x . Which of the following statements are correct? Please select ALL that apply. It's possible that there is only one correct answer. A. The estimated regression equation has a minimum B. The estimated regression equation has a maximum C. The estimated value of Y given X = 2 is 11. D. The extreme value of the estimated regression equation occurs at x = 1.5 6. [2pt] Consider a quantitative response Y, quantitative predictors X1 through X3, and a dummy variable U that takes only the values 0 and 1. How many parameters B's does the model Im (Y ~ U + x1 + (X2 + x3) * U) have? Make sure to include the intercept. Please select the best answer. A. 5 6 C. 7 D. 8