Alc Woodworking Lp
1. **Problem Statement:**
Formulate and solve the linear programming (LP) model to maximize profit from chairs and tables made with limited resources.
2. **Variables:**
Let $x$ = number of chairs, $y$ = number of tables.
3. **Objective Function:**
Maximize profit: $$Z = 20x + 16y$$
4. **Constraints:**
- Cutting time: $$3x + y \leq 24$$ (hours)
- Assembly time: $$4x + 2y \leq 48$$ (hours)
- Hockey sticks: $$2x + 5y \leq 10$$ (sticks)
- At least 2 chairs per table: $$x \geq 2y$$
- Non-negativity: $$x \geq 0, y \geq 0$$
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5. **Plotting the constraints:**
- Lines for each inequality boundary:
- Cutting time: $y = 24 - 3x$
- Assembly time: $y = 24 - 2x$
- Hockey sticks: $y = \frac{10 - 2x}{5}$
- Chairs to tables ratio: $x = 2y$
6. **Corner points (intersections of constraints):**
- Intersect $x=2y$ and $3x+y=24$:
$$3(2y)+y=24 \Rightarrow 6y + y =24 \Rightarrow 7y=24 \Rightarrow y=\frac{24}{7} \approx 3.43, x=2y=6.86$$
- Intersect $x=2y$ and $4x + 2y=48$:
$$4(2y) + 2y = 48 \Rightarrow 8y + 2y=48 \Rightarrow 10y=48 \Rightarrow y=4.8, x=9.6$$
- Intersect $x=2y$ and $2x+5y=10$:
$$2(2y)+5y=10 \Rightarrow 4y+5y=10 \Rightarrow 9y=10 \Rightarrow y=\frac{10}{9} \approx 1.11, x=2.22$$
- Intersect $3x + y=24$ and $4x + 2y=48$:
Multiply first by 2:
$$6x + 2y = 48$$
Subtract second:
$$6x+2y - (4x+2y) = 48 -48 \Rightarrow 2x = 0 \Rightarrow x=0$$
Substitute into $3x + y=24$:
$$3(0) + y = 24 \Rightarrow y=24$$
- Intersect $3x + y=24$ and $2x + 5y=10$:
Multiply first by 5:
$$15x + 5y = 120$$
Subtract second:
$$15x + 5y - (2x + 5y) = 120 - 10 \Rightarrow 13x =110 \Rightarrow x= \frac{110}{13} \approx 8.46$$
Substitute in $3x + y=24$:
$$3(8.46) + y = 24 \Rightarrow 25.38 + y=24 \Rightarrow y=-1.38$$ (Not feasible since $y\geq0$)
- Intersect $4x + 2y=48$ and $2x + 5y=10$:
Multiply second by 2:
$$4x + 10y = 20$$
Subtract first:
$$ (4x + 10y) - (4x + 2y) = 20 - 48 \Rightarrow 8y = -28 \Rightarrow y = -3.5$$ (Not feasible)
7. **Feasible corner points (non-negative and satisfy all constraints):**
- $(0,0)$
- $(0,1.11)$ from $2x + 5y=10$ and $x=0$
- $(2.22,1.11)$ from $x = 2y$ and $2x + 5y=10$
- $(6.86,3.43)$ from $x=2y$ and $3x + y=24$
- $(9.6,4.8)$ from $x=2y$ and $4x + 2y=48$
8. **Evaluate objective at corner points:**
- At $(0,0)$: $Z=0$
- At $(0,1.11)$: $Z=20(0)+16(1.11)=17.78$
- At $(2.22,1.11)$: $Z=20(2.22)+16(1.11)=44.4+17.78=62.18$
- At $(6.86,3.43)$: $Z=20(6.86)+16(3.43)=137.2+54.88=192.08$
- At $(9.6,4.8)$: $Z=20(9.6)+16(4.8)=192+76.8=268.8$
9. **Check feasibility of $(9.6,4.8)$ with hockey sticks constraint:**
$$2(9.6) + 5(4.8) = 19.2 + 24 = 43.2 > 10$$
Not feasible.
10. **Check hockey sticks constraint at $(6.86,3.43)$:**
$$2(6.86) + 5(3.43) = 13.72 + 17.15 = 30.87 > 10$$
Not feasible.
11. **Out of feasible points, the binding hockey sticks constraint reduces $y$ drastically; compute intersection between $2x + 5y=10$ and $x=2y$ (already given): $(2.22,1.11)$. This is hence likely the optimal solution.
**Final answer:**
Max profit is $$Z = 62.18$$ at approximately $$x=2.22$$ chairs and $$y=1.11$$ tables.