Beograd Inc. works 50 weeks a year and has demand for a part that is constant at 100 units a week. The cost of each unit is $200 and the company aims for a return of 20% on capital invested. Annual warehouse costs are 5% of the value of goods stored. The purchasing department costs $450,000 a year and sends out an average of 2,000 orders. Find the optimal order quantity for the part, the time between orders and the minimum cost of stocking the part.