5. Exercise 10.7 described an experiment in which 26 resis- tivity observations were made on each of six different concrete mixtures. The article cited there gave the fol- lowing sample means: 14.18, 17.94, 18.00, 18.00, 25.74, 27.67. Apply Tukey's method with a simultaneous confi- dence level of 95% to identify significant differences, and describe your findings (use MSE = 13.929).