A researcher is interested in comparing the effectiveness of four different scuba diving courses he assembles a boat full of divers 20 from each course and takes them to a nearby Barrier Reef each driver makes one dive in which he attempts to stay safely below the water for 40 minutes. the researcher then measures the number of divers from each course who successfully return to the surface. which test should the researcher use in order to see if thresia significant difference between the effectiveness of the different training courses