Group sample sizes of 42 and 42 achieve 80% power based on study finding carried out by (Galal et al., 2014) to detect a difference of 0.7 between the null hypothesis that both group means are 2.2 and the alternative hypothesis that the mean of group 2 is 1.5 with known group standard deviations of 1.5 and 0.6 and with a significance level (alpha) of 0.05000 using a two-sided Mann-Whitney test assuming that the actual distribution is uniform.