4. Maximization example-2
Find solution using Simplex method MAX Z = 30x1 + 40x2 subject to 3x1 + 2x2 <= 600 3x1 + 5x2 <= 800 5x1 + 6x2 <= 1100 and x1,x2 >= 0
Solution: Problem is
Max `Z` | `=` | `` | `30` | `x_1` | ` + ` | `40` | `x_2` |
| subject to | `` | `3` | `x_1` | ` + ` | `2` | `x_2` | ≤ | `600` | `` | `3` | `x_1` | ` + ` | `5` | `x_2` | ≤ | `800` | `` | `5` | `x_1` | ` + ` | `6` | `x_2` | ≤ | `1100` |
| and `x_1,x_2 >= 0; ` |
The problem is converted to canonical form by adding slack, surplus and artificial variables as appropiate
1. As the constraint-1 is of type '`<=`' we should add slack variable `S_1`
2. As the constraint-2 is of type '`<=`' we should add slack variable `S_2`
3. As the constraint-3 is of type '`<=`' we should add slack variable `S_3`
After introducing slack variables
Max `Z` | `=` | `` | `30` | `x_1` | ` + ` | `40` | `x_2` | ` + ` | `0` | `S_1` | ` + ` | `0` | `S_2` | ` + ` | `0` | `S_3` |
| subject to | `` | `3` | `x_1` | ` + ` | `2` | `x_2` | ` + ` | `` | `S_1` | | | | | | | = | `600` | `` | `3` | `x_1` | ` + ` | `5` | `x_2` | | | | ` + ` | `` | `S_2` | | | | = | `800` | `` | `5` | `x_1` | ` + ` | `6` | `x_2` | | | | | | | ` + ` | `` | `S_3` | = | `1100` |
| and `x_1,x_2,S_1,S_2,S_3 >= 0` |
Iteration-1 | | `C_j` | `30` | `40` | `0` | `0` | `0` | | `B` | `C_B` | `X_B` | `x_1` | `x_2` | `S_1` | `S_2` | `S_3` | MinRatio `(X_B)/(x_2)` | `S_1` | `0` | `600` | `3` | `2` | `1` | `0` | `0` | `(600)/(2)=300` | `S_2` | `0` | `800` | `3` | `(5)` | `0` | `1` | `0` | `(800)/(5)=160``->` | `S_3` | `0` | `1100` | `5` | `6` | `0` | `0` | `1` | `(1100)/(6)=183.3333` | `Z=0` | | `Z_j` | `0` | `0` | `0` | `0` | `0` | | | | `Z_j-C_j` | `-30` | `-40``uarr` | `0` | `0` | `0` | |
Negative minimum `Z_j-C_j` is `-40` and its column index is `2`. So, the entering variable is `x_2`.
Minimum ratio is `160` and its row index is `2`. So, the leaving basis variable is `S_2`.
`:.` The pivot element is `5`.
Entering `=x_2`, Departing `=S_2`, Key Element `=5`
`R_2`(new)`= R_2`(old) `-: 5``R_2`(old) = | `800` | `3` | `5` | `0` | `1` | `0` | `R_2`(new)`= R_2`(old) `-: 5` | `160` | `0.6` | `1` | `0` | `0.2` | `0` |
`R_1`(new)`= R_1`(old) - `2 R_2`(new)`R_1`(old) = | `600` | `3` | `2` | `1` | `0` | `0` | `R_2`(new) = | `160` | `0.6` | `1` | `0` | `0.2` | `0` | `2 xx R_2`(new) = | `320` | `1.2` | `2` | `0` | `0.4` | `0` | `R_1`(new)`= R_1`(old) - `2 R_2`(new) | `280` | `1.8` | `0` | `1` | `-0.4` | `0` |
`R_3`(new)`= R_3`(old) - `6 R_2`(new)`R_3`(old) = | `1100` | `5` | `6` | `0` | `0` | `1` | `R_2`(new) = | `160` | `0.6` | `1` | `0` | `0.2` | `0` | `6 xx R_2`(new) = | `960` | `3.6` | `6` | `0` | `1.2` | `0` | `R_3`(new)`= R_3`(old) - `6 R_2`(new) | `140` | `1.4` | `0` | `0` | `-1.2` | `1` |
Iteration-2 | | `C_j` | `30` | `40` | `0` | `0` | `0` | | `B` | `C_B` | `X_B` | `x_1` | `x_2` | `S_1` | `S_2` | `S_3` | MinRatio `(X_B)/(x_1)` | `S_1` | `0` | `280` | `1.8` | `0` | `1` | `-0.4` | `0` | `(280)/(1.8)=155.5556` | `x_2` | `40` | `160` | `0.6` | `1` | `0` | `0.2` | `0` | `(160)/(0.6)=266.6667` | `S_3` | `0` | `140` | `(1.4)` | `0` | `0` | `-1.2` | `1` | `(140)/(1.4)=100``->` | `Z=6400` | | `Z_j` | `24` | `40` | `0` | `8` | `0` | | | | `Z_j-C_j` | `-6``uarr` | `0` | `0` | `8` | `0` | |
Negative minimum `Z_j-C_j` is `-6` and its column index is `1`. So, the entering variable is `x_1`.
Minimum ratio is `100` and its row index is `3`. So, the leaving basis variable is `S_3`.
`:.` The pivot element is `1.4`.
Entering `=x_1`, Departing `=S_3`, Key Element `=1.4`
`R_3`(new)`= R_3`(old) `-: 1.4``R_3`(old) = | `140` | `1.4` | `0` | `0` | `-1.2` | `1` | `R_3`(new)`= R_3`(old) `-: 1.4` | `100` | `1` | `0` | `0` | `-0.8571` | `0.7143` |
`R_1`(new)`= R_1`(old) - `1.8 R_3`(new)`R_1`(old) = | `280` | `1.8` | `0` | `1` | `-0.4` | `0` | `R_3`(new) = | `100` | `1` | `0` | `0` | `-0.8571` | `0.7143` | `1.8 xx R_3`(new) = | `180` | `1.8` | `0` | `0` | `-1.5429` | `1.2857` | `R_1`(new)`= R_1`(old) - `1.8 R_3`(new) | `100` | `0` | `0` | `1` | `1.1429` | `-1.2857` |
`R_2`(new)`= R_2`(old) - `0.6 R_3`(new)`R_2`(old) = | `160` | `0.6` | `1` | `0` | `0.2` | `0` | `R_3`(new) = | `100` | `1` | `0` | `0` | `-0.8571` | `0.7143` | `0.6 xx R_3`(new) = | `60` | `0.6` | `0` | `0` | `-0.5143` | `0.4286` | `R_2`(new)`= R_2`(old) - `0.6 R_3`(new) | `100` | `0` | `1` | `0` | `0.7143` | `-0.4286` |
Iteration-3 | | `C_j` | `30` | `40` | `0` | `0` | `0` | | `B` | `C_B` | `X_B` | `x_1` | `x_2` | `S_1` | `S_2` | `S_3` | MinRatio | `S_1` | `0` | `100` | `0` | `0` | `1` | `1.1429` | `-1.2857` | | `x_2` | `40` | `100` | `0` | `1` | `0` | `0.7143` | `-0.4286` | | `x_1` | `30` | `100` | `1` | `0` | `0` | `-0.8571` | `0.7143` | | `Z=7000` | | `Z_j` | `30` | `40` | `0` | `2.8571` | `4.2857` | | | | `Z_j-C_j` | `0` | `0` | `0` | `2.8571` | `4.2857` | |
Since all `Z_j-C_j >= 0`
Hence, optimal solution is arrived with value of variables as : `x_1=100,x_2=100`
Max `Z=7000`
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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