An experiment to determine the most effective way to teach safety principles applied four different teaching methods. some employees were given programmed instruction booklets and worked through the course at their own pace. other employees attended lectures. a third group watched a television presentation, and a fourth group was divided into small discussion groups. a high score of 10 was possible on a test administered afterwards. a sample of five tests was selected from each of the four different groups (i. e there were a total of twenty tests selected). the test grade results were: sample number programmed instruction lecture tv group discussion 1 6 8 7 8 2 7 5 9 5 3 6 8 6 6 4 5 6 8 6 5 6 8 5 5 at the 0.01 level, what is the critical value