I would like to summarize this section, with an example for clarification, please $4\mathrm{.}9\mathrm{.}3$ Different Types of Carrying Charge In Section $4\mathrm{.}2,$ we assumed that the carrying charge was directly proportional to the average inventory level measured in dollars. We calculated the inventory turnover ratio using similar logic. Modifications to this inventory accounting are possible. Each can be handled with the resulting order quantity expression being somewhat more complex than Equation $4\mathrm{.}4.$ To illustrate, consider the situation where costs depend on area or volume considerations as well as the value of the inventory. $($It is intuitive that it should cost more per unit time to store a dollar of feathers than a dollar of coal.$)$ Suppose that there is a charge of w dollars per unit time per cubic foot of space allocated to an item. Assume that this space must be sufficient to handle the maximum inventory level of the item. One situation where such a change would be appropriate is where items are maintained in separate bins, and a specific bin size $($which must house the maximum inventory$)170-$ Inventory and Production Management in Supply Chains is allocated to each item. The best replenishment quantity under these circumstances is

$(2$ A D$/2$ h w$+$v r$)$

where h is the volume $($in cubic feet$)$ occupied per unit of the item.