6. In practice, MRP is a static system and it may have to be rerun each period and the production decisions reevaluated. T/F 7. Wagner-Whitin method has advantage of providing a non-optimal solution for the static problem at one level of the product structure. T/F 8. Part Period Balancing is an optimal approach that set the order horizon equal to the number of periods that most closely matches the total holding cost with the setup cost over that period. T/F 9. The EOQ method may not be very cost effective when demand patterns are highly variable over time. T/F