The yield of chemical process, expressed in percentage of the theoretical maximum, is measures with each two catalysts, A, B, and with no catlyst (Control: C). Five obeservations are made under each condition. making the ususal assumptions for an analysis of variance, test the hypothesis that there is no difference in mean yield between the three conditions. use the 5% level of significance:

Catalyst A Catalyst B Catalyst C 79.2 81.5 74.8 80.1 80.7 76.5 77.4 80.5 74.7 77.6 81.7 74.8 77.8 80.6 74.9