How does NS calculate the production quantity variance of a cost category? Inventory Cost Revaluation shows 12.5 cost and 0.33333333 quantity per unit based on manufacturing routing with 4 resources and run rate/min of 5. Cost per hour is 38. The manufacturing operation task has 5 resources (vs 4) and 15 run rate/min (vs. 5 above). Cost per hour is 38. But the WO Completion has 5 resources and 1300 minutes in total for 80 completed units and 15 scrap quantities. This resulted in 2,875 production quantity variance (no price variance).