A Product Has a Reorder Point of 110 Units, and Is

Essay

A product has a reorder point of 110 units, and is ordered four times a year. The following table shows the historical distribution of demand values observed during the reorder period.
$$\begin{array} { | c | c | } \hline \text { Demand } & \text { Probability } \\\hline 100 & .3 \\\hline 110 & .4 \\\hline 120 & .2 \\\hline 130 & .1 \\\hline\end{array}$$
Managers have noted that stockouts occur 30 percent of the time with this policy, and question whether a change in inventory policy, to include some safety stock, might be an improvement. The managers realize that any safety stock would increase the service level, but are worried about the increased costs of carrying the safety stock. Currently, stockouts are valued at $20 per unit per occurrence, while inventory carrying costs are $10 per unit per year. What is your advice?
Do higher levels of safety stock add to total costs, or not?
What level of safety stock is best?