2. The table below shows the cost of transporting one unit of stock from each of four supply points, 1 , 2, 3 and 4, to each of three demand points, \(\mathrm { A } , \mathrm { B }\) and C . It also shows the stock held at each supply point and the stock required at each demand point. A minimal cost solution is required.

1. Add a dummy demand point and appropriate values to Table 1 in the answer book. Table 2 shows an initial solution given by the north-west corner method.
   Table 3 shows some of the improvement indices for this solution. \begin{table}[h]

   	A	B	C	D
   1	20
   2	15	7
   3		18	2
   4			28	10

   \captionsetup{labelformat=empty} \caption{Table 2}
   \end{table} \begin{table}[h]

   	A	B	C	D
   1		- 13		- 9
   2			- 11
   3
   4	1	- 7

   \captionsetup{labelformat=empty} \caption{Table 3}
   \end{table}
2. Calculate the shadow costs and the missing improvement indices and enter them into Table 3 in the answer book.
3. Taking the most negative improvement index to indicate the entering square, use the steppingstone method once to obtain an improved solution. You must make your route clear and state your entering cell and exiting cell.