How are unbalanced transportation problems, where total demand is not equal to total supply, handled?

Correct answer: By introducing dummy sources or dummy destinations to balance the totals.

Explanation

The question addresses the handling of a common special case in transportation modeling, the unbalanced problem, and asks for the standard method used to make it solvable.

Other questions

Question 1

To utilize a transportation model for shipping supplies, which of the following three pieces of information are required?

Question 2

What is the primary purpose of a transportation matrix in transportation modeling?

Question 3

According to the northwest-corner rule for establishing an initial feasible solution, what is the first step in the allocation process?

Question 4

In the Arizona Plumbing problem, the initial solution using the northwest-corner rule involves five shipping assignments: 100 tubs from Des Moines to Albuquerque, 200 tubs from Evansville to Albuquerque, 100 tubs from Evansville to Boston, 100 tubs from Fort Lauderdale to Boston, and 200 tubs from Fort Lauderdale to Cleveland. The costs per unit are: Des Moines to Albuquerque ($5), Evansville to Albuquerque ($8), Evansville to Boston ($4), Fort Lauderdale to Boston ($7), and Fort Lauderdale to Cleveland ($5). What is the total cost of this initial shipping assignment?

Question 5

What is a major drawback of using the northwest-corner rule to find an initial solution?

Question 6

The intuitive lowest-cost method for finding an initial solution begins by identifying which cell in the transportation matrix?

Question 7

The stepping-stone method is used in transportation modeling to achieve what objective?

Question 8

When using the stepping-stone method, what does tracing a 'closed path' allow a manager to evaluate?

Question 9

In the stepping-stone method, what does a calculated improvement index for an unused square represent?

Question 10

When is an optimal solution reached in the stepping-stone method?

Question 11

In the Arizona Plumbing problem, the initial northwest-corner solution is evaluated using the stepping-stone method. The unused route from Fort Lauderdale to Albuquerque has a closed path involving squares with costs of $9 (Fort Lauderdale-Albuquerque, +), $7 (Fort Lauderdale-Boston, -), $4 (Evansville-Boston, +), and $8 (Evansville-Albuquerque, -). What is the improvement index for this route?

Question 12

If the stepping-stone method reveals an unused route with an improvement index of -2, what is the next step to improve the solution?

Question 13

When reallocating units along a closed path in the stepping-stone method, how is the maximum quantity to be shipped on the new route determined?

Question 15

If total demand is 800 units and total supply is 700 units in a transportation problem, how would you balance it?

Question 16

What are the shipping cost coefficients assigned to the squares in a dummy source row or dummy destination column?

Question 17

What is the definition of a degenerate solution in a transportation problem?

Question 18

To apply the stepping-stone method, a non-degenerate solution must satisfy a specific rule regarding the number of occupied shipping routes. What is this rule?

Question 19

How are degenerate problems handled in the stepping-stone method?

Question 20

In a transportation problem with 4 factories (sources) and 5 warehouses (destinations), how many occupied routes must a non-degenerate solution have?

Question 21

When resolving degeneracy, where must the artificial occupied cell be placed?

Question 22

In the solved problem for Williams Auto Top Carriers, opening a plant in New Orleans has an initial total cost of $23,600. After one stepping-stone iteration, what is the new total cost?

Question 23

In the Williams Auto Top Carriers problem, the total cost for one auto top carrier from Atlanta to Los Angeles is stated as $14. How is this figure derived?

Question 24

After improving the solution for the Williams New Orleans plant to a total cost of $20,000, the improvement indices for the two unused routes (Atlanta-Los Angeles and New Orleans-Los Angeles) are calculated as +6 and +2, respectively. What does this signify?

Question 25

The transportation model is described as a form of what other mathematical technique?

Question 26

What is the primary difference in the allocation process between the northwest-corner rule and the intuitive lowest-cost method?

Question 27

In a problem with 3 sources and 3 destinations, you have found an initial solution using the northwest-corner rule. You have 5 occupied cells. Can you proceed with the stepping-stone method?

Question 28

The stepping-stone method is described as an iterative technique. What does 'iterative' mean in this context?

Question 29

In the stepping-stone method, the closed path traced for an unused square can only make horizontal and vertical moves. At what cells is it permissible to turn a corner?

Question 30

In the Arizona Plumbing problem, after one iteration, the total cost is reduced from $4,200 to $4,000. What caused this $200 reduction?

Question 31

If you are solving a transportation problem and find that all possible initial solutions are degenerate, what is the most likely cause?

Question 32

Which of the two methods for finding an initial solution is generally preferred because it tends to provide a better starting point?

Question 33

A firm has 2 factories with supplies of 100 and 60 units. It has 3 destinations with demands of 50, 80, and 70 units. What is the first step in setting up the transportation matrix?

Question 34

What is the key advantage of a transportation model when a company like Williams Auto Top Carriers is deciding on a new plant location?

Question 35

In the solved problem C.1, the improvement index for the Atlanta-New York route is -6. This is calculated as +11 (Atlanta-New York) - 14 (Atlanta-Los Angeles) + 9 (Tulsa-Los Angeles) - 12 (Tulsa-New York). Where do the costs like $11 and $14 come from?

Question 36

Consider a transportation problem with sources in Mexico City, Detroit, and Ottawa, and destinations in Los Angeles, Calgary, and Panama City. Supply from Mexico City is 100. Demand in Los Angeles is 50. The cost to ship from Mexico City to Los Angeles is $6. Using the northwest-corner method, what is the first allocation made?

Question 37

If a transportation model is solved and the optimal solution has two routes with improvement indices of zero, what does this indicate?

Question 38

In the solved problem C.2, the Williams Auto Top Carriers problem is formulated as a linear programming model. The constraint 'XAtl,LA + XAtl,NY <= 600' is created. What does this constraint represent?

Question 39

In the solved problem C.2 linear programming formulation for Williams Auto, the constraint 'XAtl,LA + XTul,LA + XNO,LA >= 800' is created. What does this constraint represent?

Question 40

Can the stepping-stone method be used to solve maximization problems as well as minimization problems?

Question 41

An origin point or source in a transportation model can be which of the following?

Question 42

The final step of the intuitive lowest-cost method is repeated until when?

Question 43

If you perform a stepping-stone iteration and reallocate 100 units along a path where the smallest number in a 'minus' square was 100, what happens to the cell where that smallest number was located?

Question 44

Why must the closed path in the stepping-stone method alternate plus and minus signs on its corner squares?

Question 45

You are given a transportation problem where the total supply is 1,000 units and the total demand is 1,200 units. You add a dummy source with a supply of 200 units. What can be said about the units allocated from this dummy source in the final optimal solution?

Question 46

What is the result of using the intuitive lowest-cost method on the Arizona Plumbing problem data? The costs are: D-A $5, D-B $4, D-C $3; E-A $8, E-B $4, E-C $3; F-A $9, F-B $7, F-C $5. Supply is D:100, E:300, F:300. Demand is A:300, B:200, C:200.

Question 47

The solution from the intuitive lowest-cost method for the Arizona Plumbing problem has a total cost of $4,100. Is this solution optimal?

Question 48

Consider the problem with sources X, Y, Z (supplies 100, 50, 75) and destinations A, B, C (demands 50, 80, 70). The costs are X-C: $12, Y-C: $9, Z-C: $14. Total supply is 225, total demand is 200. After adding a dummy destination D with demand 25, you apply the intuitive lowest-cost method. The cost for Y-C is the lowest in its column. How many units are allocated to Y-C?

Question 49

If you are solving a transportation problem manually, and the final optimal solution has two empty cells with improvement indices of +3 and 0 respectively, what can you conclude?

Question 50

When can a transportation model be useful in an aggregate planning context, as mentioned in the chapter summary?