4. A firm manufacturing a single product has three plants P-I, P-II and P-III. They have produced 60, 35 and 40 units, respectively during this month. The firm had made a commitment to sell 22 units to customer C-I, 45 units to customer C-II, 20 units to customer C-III, 18 units to customer C-IV and 30 units to customer C-V. Find the minimum possible transportation cost of transporting the manufactured product to the five customers. The net unit cost of transporting from the three plants to five customers is provided in the following table. P-I P-II P-III C-I 4 2 3 C-II 1 3 5 C-III 3 2 2 C-IV 4 2 4 C-V 4 3 4