Dan Bumblauskas is the owner of a small Iowa company that produces electric knives used to cut fabric. The annual demand is for 8,000 knives, and Dan produces the knives in batches. On average, Dan can produce C knives per day; during the production process, demand has been about 40 knives per day. The cost to set up the production process is $100, and it costs Dan $.80 to carry a knife for 1 year. How many knives should Dan produce in each batch?