Chapter 14, Problem 38PS

Suppose $X_1$ is a numerical variable and $X_2$ is a dummy variable with two categories and the regression equation for a sample of $n=20$ is

${\hat{Y}}_i=6+4X_{1i}+2X_{2i}$

a. Interpret the regression coefficient associated with variable $X_{1.}$

b. Interpret the regression coefficient associated with variable $X_{2.}$

c. Suppose that the $t_{STAT}$ test statistic for testing the contribution of variable $X_2$ is 3.27. At the 0.05 level of significance, is there evidence that variable $X_2$ makes a significant contribution to the model?