3. The demand for a product for six periods is 50, 40, 60, 70, 80 and 90 units, respectively. Order cost $200 per order; the cost of obtaining possession is $0.5 per piece and period has been given. Calculate the order quantities and total costs using the following methods calculate: a. (20 points) Wagner-Whitin algorithm. b. (20 points) Heuristic approach to part-period balancing