An army wants to move troops from 3 training camps to 4 different bases. How should | ||||||
the troops be moved to minimize cost? | ||||||
Moving Cost Per Man | ||||||
Base 1 | Base 2 | Base 3 | Base 4 | |||
Camp 1 | $34 | $26 | $29 | $31 | ||
Camp 2 | $42 | $33 | $28 | $35 | ||
Camp 3 | $36 | $29 | $32 | $38 | ||
Number Of Troops Moved | ||||||
Base 1 | Base 2 | Base 3 | Base 4 | Total | Available | |
Camp 1 | 100 | 100 | 100 | 100 | 400 | 500 |
Camp 2 | 100 | 100 | 100 | 100 | 400 | 400 |
Camp 3 | 100 | 100 | 100 | 100 | 400 | 400 |
Total | 300 | 300 | 300 | 300 | ||
Required | 200 | 250 | 350 | 300 | ||
Cost | $11,200 | $8,800 | $8,900 | $10,400 | $39,300 | |
Problem | ||||||
An army wants to move troops from 3 training camps to 4 different bases. All costs of moving a | ||||||
soldier from any camp to any base are known. How should the army move the troops to | ||||||
minimize cost? | ||||||
Solution | ||||||
1) The variables are the number of soldiers that are moved from each camp to each base. On | ||||||
worksheet Troops these are given the name Troops_moved. | ||||||
2) The constraints are | ||||||
Troops_moved >= 0 via the Assume Non-Negative option | ||||||
Troops_per_camp <= Troops_available | ||||||
Troops_per_base = Troops_required | ||||||
3) The objective is to minimize the total cost. This is defined on the worksheet as Total_cost. | ||||||
Remarks | ||||||
This model is a transportation model, like those shown in the Logistics Examples workbook. You | ||||||
might wonder why there is no constraint to assure that the numbers of troops moved are integers. | ||||||
It is a mathematical property of these types of problems that if the constants in the constraints are | ||||||
integers, the solution values for the variables are always integers. It is beyond the scope of these | ||||||
examples to further explore this. | ||||||