Consider the following Cost, Capacity and Demand data

Regular time labor cost: $10 per hour Overtime labor cost: $15 per hour Backorder cost per unit: $20 Inventory holding cost per unit: $10 Labour standard per unit: 0.6 hours Regular time available/period: 30 hours/employee Overtime available/period: 30 hours/employee

Beginning workforce: 15 employees Beginning inventory: 0 units Demand data Period 1: 813 units Period 2: 864 units Period 3: 853 units Period 4: 840 units

If the firm uses a mixed strategy where only backorders are used beside regular labour, the backorder cost for the planning horizon will be