The Annual Demand, Ordering Cost, and the Inventory Carrying Cost

Essay

The annual demand, ordering cost, and the inventory carrying cost rate for a certain item are D = 600 units, S = $20/order and I = 30% of item price. Price is established by the following quantity discount schedule. What should the order quantity be in order to minimize the total annual cost?
$$\begin{array} {| l | l | l | l | } \hline \text { Quantity } & 1 \text { to } 49 & 50 \text { to } 249 & 250 \text { and up } \\\hline \text { Price } & \$ 5.00 \text { per unit } & \$ 4.50 \text { per unit } & \$ 4.10 \text { per unit } \\\hline\end{array}$$