the number of kangaroo rats living on an island on Jan 1, 2020 was 634,000. how many rats would be expected to be on the island on Jan 1 , 2025 if the birth rate was 1.40 baby rats/ rat-year and predation and other causes result in a net mortality rate of 0.730 rats/rat-year. assume rat immigration and emmigration from shipping activities at harbors are 0.01 and 0.03 rats/rat-year respectvily