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Consider the following tansportation problem :

F1F2F3F4
W1193030107
W2703040609
W3408703018
5871434

(Columns: Factory F1 to F4; rows: Warehouse W1 to W3.)

Let Xij be the allocation in the (i, j)th cell. The solution (x11 = 5, x14 = 2, x22 = 2, x23 = 7, x32 = 6, x34 = 12) is :

  • A.Initial solution by Vogel's method
  • B.Optimal solution
  • C.Initial solution by least cost method
  • D.Suboptimal solution which can be improved

Answer: B

The given allocation is the Optimal solution.

It uses 6 cells, equal to m + n - 1 = 3 + 4 - 1, so it is a basic solution. Test it with the u-v (MODI) method, setting \(u_{1} = 0\) and using \(u_{i} + v_{j} = c_{ij}\) in the occupied cells:

\[ \begin{aligned} v_{1} &= 19,\ v_{4} = 10,\ u_{3} = 20 \\ v_{2} &= -12,\ u_{2} = 42,\ v_{3} = -2 \end{aligned} \]

The reduced costs \(c_{ij} - u_{i} - v_{j}\) of the empty cells are 42, 32, 9, 8, 1 and 52, all positive, so no reallocation can lower the cost and the solution is optimal (total cost 863). It is not the Vogel or least cost starting solution: both of those first fill cell (3, 2), the lowest-cost cell at 8, with all 8 units, not 6.

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