Answer
Time of a drilling whose depth is 100 feet in dry conditions:
The 95% confidence interval is between 7.59801 and 8.19550 minutes.
(for the mean time of all drilling whose depth is 100 feet in dry conditions)
The 95% prediction interval is between 6.98974 and 8.80376 minutes.
(for the time of a particular drilling whose depth is 100 feet in dry conditions)
Work Step by Step
With the results from item (b) still available in MINITAB:
Select Stats -> Regression -> Regression -> Predict
Enter 100 and 1 in the first row of the table.
Click in Options and enter the level of confidence. Click OK.
Click OK.
