1. **Problem Statement:**
A car hire company has one car at each of five depots a, b, c, d, and e. A customer in each of five cities A, B, C, D, and E requires a car. The distances (in km) between depots and cities are given. We need to assign cars to cities to minimize total distance traveled.
2. **Method:**
This is an assignment problem, solved using the Hungarian Algorithm which finds the minimum cost matching in a cost matrix.
3. **Distance matrix:**
$$\begin{bmatrix} 200 & 150 & 180 & 200 & 250 \\ 180 & 200 & 120 & 140 & 150 \\ 210 & 230 & 250 & 270 & 250 \\ 170 & 180 & 210 & 230 & 200 \\ 180 & 180 & 160 & 190 & 200 \end{bmatrix}$$
4. **Step 1: Row reduction** (subtract minimum of each row from all elements in that row):
- Row A min = 150, new row A: $[200-150, 150-150, 180-150, 200-150, 250-150] = [50, 0, 30, 50, 100]$
- Row B min = 120, new row B: $[180-120, 200-120, 120-120, 140-120, 150-120] = [60, 80, 0, 20, 30]$
- Row C min = 210, new row C: $[210-210, 230-210, 250-210, 270-210, 250-210] = [0, 20, 40, 60, 40]$
- Row D min = 170, new row D: $[170-170, 180-170, 210-170, 230-170, 200-170] = [0, 10, 40, 60, 30]$
- Row E min = 160, new row E: $[180-160, 180-160, 160-160, 190-160, 200-160] = [20, 20, 0, 30, 40]$
5. **Step 2: Column reduction** (subtract minimum of each column from all elements in that column):
- Column 1 min = 0, no change
- Column 2 min = 0, no change
- Column 3 min = 0, no change
- Column 4 min = 20, new column 4: $[50-20, 20-20, 60-20, 60-20, 30-20] = [30, 0, 40, 40, 10]$
- Column 5 min = 30, new column 5: $[100-30, 30-30, 40-30, 30-30, 40-30] = [70, 0, 10, 0, 10]$
6. **Reduced matrix:**
$$\begin{bmatrix} 50 & 0 & 30 & 30 & 70 \\ 60 & 80 & 0 & 0 & 0 \\ 0 & 20 & 40 & 40 & 10 \\ 0 & 10 & 40 & 40 & 0 \\ 20 & 20 & 0 & 10 & 10 \end{bmatrix}$$
7. **Step 3: Assignment**
- Assign city A to depot b (0 cost)
- Assign city B to depot d or e (both 0 cost), choose depot d
- Assign city C to depot a (0 cost)
- Assign city D to depot e (0 cost)
- Assign city E to depot c (0 cost)
8. **Final assignment:**
- A → b (distance 150)
- B → d (distance 140)
- C → a (distance 210)
- D → e (distance 200)
- E → c (distance 160)
9. **Total minimum distance:**
$$150 + 140 + 210 + 200 + 160 = 860$$
**Answer:** Assign cars as above to minimize total distance traveled to 860 km.
Car Assignment 8A395B
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.