Answer
Lower Bound = 20.4 cm, Upper Bound = 48.9 cm. Hence, we are 95% confident that the mean standard deviation diameter of a Douglas fir tree in the western Washington Cascades is between 20.4 and 48.9 cm.
Work Step by Step
In Minitab, from the stats menu, select basic statistics and the 1 variance. Fill in the fields and click ok.