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Determine the optimal distribution policy. Use VAM to find initial solution and MODI for finding optimal solution.

enter image description here

Mumbai University > Mechanical Engineering > Sem 7 > Operations Research

Marks: 10 Marks

Year: Dec 2015

1 Answer
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As demand is more than supply, we introduce a dummy row, whose supply is difference between total demand and total supply with cost coefficient of the cells as zero.

| a | W | X | Y | Z| | | |-|-|-|-|-|-|-|
|A| 17| 20| 14| 12| 60| [2]| |B| 15| 21| 25| 14| 75| [1]| |C| 15| 14| 15| 16| 105| [1]| |DUMMY| 0 (50)| 0| 0| 0| 50/0| [0]| | | 50/0| 65| 75| 100| | |
| | [15] ↑| [14]| [14]| [12]| | |

| | X| Y| Z| | | |-|-|-|-|-|-|
|A| 20| 14| 12| 60| [2]| |B| 21| 25| 14 (75)| 75/0| [7]←| |C| 14| 15| 16| 105| [1]| | | 65| 75| 100/25| | |
| | [6]| [1]| [2]|  | |

| | X| Y| Z| | | |-|-|-|-|-|-|
|A| 20| 14| 12| 60| [2]| |C| 14 (65) |15| 16| 105/40| [1]| | | 65/0| 75| 25| | |
| | [6] ↑| [1]| [4]| | |

| | Y| Z| | | |-|-|-|-|
|A| 14| 12 (25)| 60/35| [2]| |C| 15| 16| 40| [1]| | | 75| 25/0| | |
| | [1]| [4] ↑| | |

  Y  
A 14 (35) 35/0
C 15 (40) 40/0
  75/0  

The single final matrix showing allocations is shown below,

| | W| X| Y| Z| | | | | |
|-|-|-|-|
|A| 17| 20| 14 (35)| 12 (25)| 60| [2]| [2]| [2]| [2]| |B| 15| 21| 25| 14 (75)| 75/0| [1]| [7]←|  |  | |C| 15| 14 (65)| 15 (40)| 16| 105/40/0| [1]| [1]| [1]| [2]| |DUMMY| 0 (50)| 0| 0| 0| 50/0| [0]| | | |
| | 50/0| 65/0| 75/0| 100/25/0| | | | |
| | [15] ↑| [14]| [14]| [12] | | | | |
|  | | [6]| [1] |[2] | | | | |
| | | [6] ↑| [1]| [4] | | | | |
| | | | [1]| [4] ↑ | | | | |

Transportation cost :-

Z =1435+1225+1475+1465+1540+050=3350

But, m + n – 1 = 7 and no. of allocations = 8, here degeneracy exists.

The minimum cost in the unallocated cells is 0. Selecting Dummy-Z cell arbitrarily for assigning ‘ɛ’ allocation to it. Also checking for optimality by UV rule/ MODI method.

  v1 v2 v3 v4
u1 17 20 14 (35) 12 (25)
u2 15 21 25 14 (75)
u3 15 14 (65) 15 (40) 16
u4 0 (50) 0 0 0 (ɛ)

u4+v1=0,u3+v2=14,u1+v3=14,u1+v4=12,u2+v4=14,u3+v2=14,u3+v3=15,u4+v4=0Letu1=0,v3=14,v4=12,u2=2,u3=1,v2=13,u4=12,v1=12.

enter image description here

As we can see θ = 35, again checking for optimality with new allocations.

  v1 = 13 v2 = 12 v3 = 13 v4 = 12
u1 = 0 17 (4) 20 (8) 14 (1) 12 60
u2 = 2 15 35 21 (7) 25 (10) 14 40
u3 = 2 15 (0) 14 65 15 40 16 (2)
u4 = -13 0 15 0 (1) 0 35 0 (1)

No negative numbers are present, which shows we have obtained the optimal solution.

  W X Y Z
A 17 20 14 12 60
B 15 35 21 25 14 40
C 15 14 65 15 40 16
DUMMY 0 15 0 0 35 0

Minimum transportation cost =1535+015+1465+1540+035+1260+1440=3315.

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