Reconsider the port alcohol content data from Exercise 14.22. A normal probability plot casts some doubt on the assumption of population normality. However, a dotplot shows a reasonable amount of symmetry, and the mean, median, and 5% trimmed mean are 19.257, 19.200, and 19.209, respectively. Use the Wilcoxon test at significance level .01 to decide whether there is substantial evidence for concluding that true average content exceeds 18.5.