Determine the optimal inventory policy when the goods are to be ordered at the end of every month from now on. The cost of bringing the inventory level up to y when x already is available is given by 2(y x). Similarly, the cost of having the monthly demand D exceed y is given by 5(D y). The probability density function for D is given by 
The holding cost when y exceeds D is given by y D. A monthly discount factor of 0.95 is used.