Define a method called changePopulation that could be added to the definition of the class SpeciesSecondTry in Listing 5.6. This method has two parameters. One parameter, named area, is of type double and gives the area occupied by the species in square miles. The other parameter, named numberPerMile, is of type int and gives the desired number of individuals per square mile. The method changePopulation changes the value of the instance variable population so that the number of individuals per square mile is (approximately) equal to numberPerMile.
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