A grain elevator not only buys grains from nearby farmers but also sells them seeds and chemicals. But how much of each item will be sold in a given year is uncertain, making the decision on the purchase quantity difficult. Consider the ordering of a particular herbicide by a specific grain elevator manager. Each unit weighs 50 kg. The selling price is $56.93 per unit, and the purchase cost (including the transportation cost) is $45.54. Any excess herbicide after the growing season is transported to a warehouse at the cost of $1.09 per unit, and held over winter at the holding cost rate of 10 percent of unit cost per year ( which equals 5 percent for half a year-the approximate length of winter). It is estimated that 10 percent of shortage will be lost. The rest will incur $2.19 per unit in expediting cost from the supplier. The elevator manager estimates that the demand for this herbicide can take values of 100, 400, and 1,500 units with probabilities of 0.1, 0.5, and 0.4, respectively. What is the best stocking level?