Answer
After removing Cut:
$ŷ =-36+11382x_1-613.2x_2-473.4x_3$
Work Step by Step
According to results obtained in part (c), we must remove the explanatory variable Cut because its P-value is greater than $α=0.05$.
In MINITAB, enter the Carat values in C1, the Color values in C2, the Clarity values in C3 and the Price values in C5.
Select Stats -> Regression -> Regression -> Fit Regression Model
Enter C5 in "Responses" and C1 C2 C3 in "Continuous Predictors"
The least-squares regression line will be shown in "Regression Equation", where C5 is $ŷ$ (Price), C1 is $x_1$ (Carat), C2 is $x_2$ (Color) and C3 is $x_3$ (Clarity).
$ŷ =-36+11382x_1-613.2x_2-473.4x_3$
Now, the three P-values are less than $α=0.05$.
