A developmental psychologist is determining problem solving capability in children. Random samples of 7, 9, and 11 year olds children are obtained with the n=8 in each sample and each child is given the problem solving test in which higher scores point out better problem solving. The data are as follows: 7 year olds: mean = 8.1 s²= 2.45; 9 year olds: mean= 9.44, s²= 4.7; 11 year olds: mean = 14.2, s² = 5.92 and sum of X squared EX² = 2941.60. What can be concluded regarding age differences in problem solving capability?