Demand for fasteners at Turan Inc. is 20,000 boxes per month. Holding cost at Turan is 20 percent per box per year. Each order incurs a fixed cost of $400. The supplier offers an all unit discount pricing scheme with a price of $5 per box for orders under 30,000 and a price of $4.90 for all orders of 30,000 or more. How many boxes should Turan order per replenishment?