Find the optimum number of batches (to the nearest whole number) of an item that should be produced annually (in order to minimize cost) if 280,000 units are to be made, it costs $4 to store a unit for one year, and it costs $360 to set up the factory to produce each batch.
◦ 41 batches
◦ 30 batches
◦ 39 batches
◦ 28 batches