1.) In Roosevelt National Forest, the rangers took random samples of live aspen trees and measured the base circumference of each tree.Base circumference of live aspen trees are normally distributed.A sample of 20 trees had a mean circumference of 15.71 inches.The sample standard deviation is 4.63 inches. To find a 95% confidence interval for the mean circumference of all aspen trees in Roosevelt National Forest from this data, the correct statistical procedure would be a(Circle one):

(a)Z-Interval

(b)T-Interval

(c)Z-Test

(d)T-Test

(e)1PropZInt