Answer
The 95% confidence interval is between 6567.88 and 7415.44 dollars.
(for the mean price of all diamonds with 0.85 carat, color E, clarity VVS1)
Work Step by Step
With the results from item (e) still available in MINITAB:
Select Stats -> Regression -> Regression -> Predict
Enter 0.85, 2 and 3 in the first row of the table.
Click in Options and enter the level of confidence. Click OK.
Click OK.
