Data on shipping cost, demand, and available supply for a transportation problem is given below. In this model, Xij is defined as units shipped from Plant i (i = 1, 2) to Customer j (j = 1, 2, 3).

3. Part of the optimal solution is as follows. X11 = 0, X13 = 900, X21 = 300, X23 = 0. Determine the rest of the optimal solution.

a) X12=0, X22=500

b) X12=1800, X22=0

c) X12=1300, X22=500

d) X12=1600, X22=200

4. Which of the following statements is true if the available supply in Plant 2 is increased by 500 (from 500 to 1000)?

a) The optimal total cost will decrease by 1000

b) The optimal total cost will decrease by 4000

c) The optimal total cost will increase but we do not know how much

d) There is not enough information to determine if the optimal total cost increases or decreases

\begin{tabular}{|c|c|c|c|} \cline { 2 - 4 } \multicolumn{1}{c|}{} & \multicolumn{3}{c}{ SHIPPING COST (\$/unit): } \\ \cline { 2 - 4 } \multicolumn{1}{c|}{} & ToCUSTOMER1 & ToCUSTOMER2 & ToCUSTOMER3 \\ \hline From PLANT 1 & 10 & 10 & 3 \\ \hline From PLANT 2 & 7 & 8 & 8 \\ \hline DEMAND(units/month) & 300 & 1800 & 900 \\ \hline \end{tabular} SUPPLY AVAILABLE (units/month) 3000 500