Mixture Inventory Model with Backorders and Lost Sales for Variable Lead Time

In a recent paper, Ben-Daya and Raouf presented a continuous review inventory model in which they considered both lead time and the order quantity as decision variables where the shortages are neglected. We assume here that the shortages are allowed and we extend the Ben-Daya and Raouf model by adding the stockout cost. Furthermore, the effects of parameters are also included.