In such an experiment, different concentrations of the toxic chemical can be added to different ponds, and the number of fishes that die in each pond can be recorded after 1 week. The data from this experiment can then be used to create a graph that shows the relationship between the amount of toxic chemical and the number of fishes that died.
If the graph shows a positive correlation, it means that the amount of toxic chemical is a significant factor in the number of fishes that died. This information can then be used to develop strategies to reduce the amount of toxic chemical in pond water and protect fish populations.