When the chestnut blight fungus, Cryphonectria parasitica, first entered Harvard Forest its population was growing exponentially. Anita MacTavish, a graduate student working on chestnut blight, estimated that the ANNUAL per capita growth rate (r) of the fungus 3.2 new cankers per year. Of Cryphonectria parasitica population size (Measured in number of cankers) was 313 in 1935, predict the population size in 1938.