The following data represent the operating time in hours for 4 types of pocket calculators before a recharge is required. Use the Kruskal-Wallis test, at the 0.01 level of significance, test the hypothesis that the operating times for all four calculators are equal. F x 1 0 1 Fx 2 0 2 Fx 3 0 3 Fx 4 0 4 6.1 5.9 7.1 5.3 6.2 5.8 7.1 4.9 6.5 5.9 7.2 6.1 6.2 5.1 7.3 7.1 6.3 1.0 7.4 4.9