The data shown in Table 6.31 relate to the effectiveness of several insecticides. One hundred insects of a particular species were put into a chamber and exposed to an insecticide for 15 s. The procedure was applied in random order six times for each of four insecticides. The response is the number of dead insects. Based on these data, can you make a recommendation? Check assumptions! 

Table 6.31 Data for Exercise 15. Insecticide A B C D 85 90 93 98 82 92 94 98 83 90 96 100 88 91 95 97 89 93 96. 97 92 81 94 99