A sample of 56 research cotton samples resulted in a sample average percentage elongation of 8.17 and a sample standard deviation of 1.42 (“An Apparent Relation Between the Spiral Angle , the Percent Elongation E1, and the Dimensions of the Cotton Fiber,” Textile Research J., 1978:

407–410). Calculate a 95% large-sample CI for the true average percentage elongation . What assumptions are you making about the distribution of percentage elongation?