The planning engineer is doing his medium-term plans. Demand for the next 3 months is estimated to be 3300, 2600, 3500 in terms of aggregate units. The company has unchanging workforce size of 60 and each worker is capable of producing 50 units per month of regular production which costs $100 per unit. The company has an overtime capacity of 1000 units. The overtime cost is $50 per unit. In addition, Shortage is not allowed. The inventory cost is $20 per unit per month. The beginning inventory is 100. Formulate the transportation model matrix. Solve the transportation problem using Northwest Corner method.