A farmer grows apples on her 600 acre farm and must cope with occasional infestations of worms. If she refrains from using pesticides, she can get a premium for "organically grown" produce and her profits per acre increase by $600 if there is no infestation, but decrease by $400 if there is. If she does use pesticides and there is an infestation, her crop is saved and the resulting apple shortage (since other farms are decimated) raises her profits by $500 per acre. Otherwise, her profits remain at their usual levels. How should she divide her farm into a "pesticide-free" zone and a "pesticide-use" zone? What will be her expected increase in profits per acre with this strategy?