In Problem 8, suppose that the daily demand at area 3 drops to 4 million gallons. Surplus
production at refineries 1 and 2 is diverted to other distribution areas by truck. The transportation
cost per 100 gallons is $1.50 from refinery 1 and $2.20 from refinery 2. Refinery
3 can divert its surplus production to other chemical processes within the plant.
(a) Formulate the problem as a transportation model.
(b) Determine the optimum shipping schedule.