Example 1: The Transportation Problem

 

There are three plants making widgets, and three widget-buying customers.  Each plant has a fixed supply, and each customer has a fixed demand.  The table below shows the supply and demand information, along with the cost of shipping from a given plant to a given customer.

 

 

Customer 1

Customer 2

Customer 3

Total Supply

Plant 1

6

1

4

100

Plant 2

14

5

8

300

Plant 3

20

14

15

300

Total Demand

300

200

200

700

 

Our objective is to minimize the shipping cost.

 

Formulate the Problem:

Define 9 variables, each with a double subscript that refers to the given Plant and Customer.

 

Objective Function :

Min Z = 6x11 + 1x12 + 4x13 + 14x21 + 5x22 + 8x23 + 20x31 + 14x32 + 15x33

ST :          x11 + x12 + x13 <= 100

            x21 + x22 + x23 <= 300

x31 + x32 + x33 <= 300

x11 + x21 + x31  = 300

            x12 + x22 + x32  = 200

x13 + x23 + x33  = 200

 

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