7. The diameter of the Douglas fir tree is measured at a height of 1.37 meters. The following data represents the diameter in centimeters of a random sample of 12 Douglas firs in the western Washington cascades. 15619014717315918116213010114711310 9a. Obtain a point estimate for the mean and standard deviation diameter of a Douglas fir tree in the western Washington Cascades. b. Construct a 95% confidence interval for the mean diameter of a Douglas fir tree in the western Washington Cascades. Interpret the confidence interval. c.Construct a 95% confidence interval for the standard deviation diameter of a Douglas fir tree in the western Washington Cascades. Interpret the confidence interval.