/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 8 You are given the final simplex ... [FREE SOLUTION] | 91Ó°ÊÓ

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You are given the final simplex tableau for the dual problem. Give the solution to the primal problem and the solution to the associated dual problem. Problem: Minimize \(C=3 x+2 y\) subject to \(\begin{aligned} 5 x+y & \geq 10 \\ 2 x+2 y & \geq 12 \\ x+4 y & \geq 12 \\ x \geq 0, y & \geq 0 \end{aligned}\) Final tablcau: $$ \begin{array}{rrrrrr|r} u & v & w & x & y & P & \text { Constant } \\ \hline 1 & 0 & -\frac{1}{4} & \frac{1}{4} & -\frac{1}{4} & 0 & \frac{1}{4} \\ 0 & 1 & \frac{19}{8} & -\frac{1}{8} & \frac{5}{8} & 0 & \frac{7}{8} \\ \hline 0 & 0 & 9 & 1 & 5 & 1 & 13 \end{array} $$

Short Answer

Expert verified
The solution for the primal problem is (x, y) = (13, 0) with the optimal cost C = 39. The associated dual problem has the solution (u, v, w) = (1/4, 7/8, 0) and an optimal cost Z = 13.

Step by step solution

01

Identify the basic variables

In the given final tableau, the columns corresponding to variables x and y are identity-like columns with only one non-zero value of 1 and other values as zero. The variables x and y are basic variables in this case.
02

Read solution for primal and dual

As x and y are basic variables in the final tableau, the solution for the primal problem can be found directly from the tableau. Primal solution: x = 13 y = 0 Now, let's find the associated solution for the dual problem, using the final tableau values for the slack-form variables (u, v, and w). Dual solution: u = 1/4 v = 7/8 w = 0 The primal problem solution (x, y) = (13, 0), and the associated dual problem solution (u, v, w) = (1/4, 7/8, 0).
03

Calculate the optimal costs for the primal and dual problem

Let's compute the optimal costs for the primal and dual problem. First, use the primal solution (x, y) to calculate the value of the objective function C: C = 3x + 2y C = 3(13) + 2(0) C = 39 Now, let's compute the optimal cost for the associated dual problem using the dual solution (u, v, w): \(Z = 10u + 12v + 12w\) \(Z = 10(1/4) + 12(7/8) + 12(0)\) \(Z = 2.5 + 10.5\) \(Z = 13\) So, the optimal costs for the primal and dual problems are C = 39 and Z = 13. In conclusion, the solution for the primal problem is (x, y) = (13, 0) with the optimal cost C = 39. The associated dual problem has the solution (u, v, w) = (1/4, 7/8, 0) and an optimal cost Z = 13.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Primal Problem
The primal problem involves the original objective of minimizing or maximizing a function subject to a set of constraints. In this exercise, we need to minimize the function:\[ C = 3x + 2y \] This is subject to the constraints:\[\begin{aligned}5x + y & \geq 10, \2x + 2y & \geq 12, \x + 4y & \geq 12, \x & \geq 0, y & \geq 0. \\end{aligned}\]The primal problem is fundamental in linear programming, where the goal is to find the values of variables (here, \(x\) and \(y\)) that optimize the objective function while satisfying all given constraints. For the given problem, the solution was attained using the final tableau from the simplex method, giving us \(x = 13\) and \(y = 0\). This shows the optimal combination of \(x\) and \(y\) for minimizing \(C\).
Dual Problem
The dual problem arises from the primal problem and relates directly to its constraints. For every primal problem, there exists a dual problem that offers a deeper insight or alternative perspective. In this case, the dual problem solution helps us understand how changes in the resources or constraints affect the overall system. The variables for the dual are typically slack or surplus variables originally associated with the primal constraints.The final tableau provides these dual variables: \(u, v, w\) which in this exercise correspond to the primal constraints. The solutions found for these dual variables are \(u = \frac{1}{4}\), \(v = \frac{7}{8}\), and \(w = 0\).Interpreting dual variable values helps in resource allocation and economic interpretation, effectively acting as shadow prices. These dual solutions give insights into the pressure put on the primal constraints.
Objective Function
The objective function is the primary equation that we seek to optimize, either minimize or maximize. In our exercise, the objective function is given as:\[ C = 3x + 2y \]The coefficients 3 and 2 represent the cost associated with each unit of \(x\) and \(y\) respectively. The role of the objective function is crucial, as it quantifies what you aim to achieve through optimization, guiding the simplex method toward the best solution. In the context of this problem, the simplex method identifies the optimal values for \(x\) and \(y\) that minimize \(C\) under the provided constraints.Upon solving the primal problem, when \(x = 13\) and \(y = 0\), the minimized cost or objective function value is \(C = 39\). This gives us the least possible `cost` given the constraints, effectively solving our optimization problem.
Optimal Solution
The optimal solution refers to the set of values for the decision variables that optimize the objective function while adhering to all the problem's constraints. In linear programming, the optimal solution achieved by the simplex method directly reflects the conclusion of best possible results for the given linear equations.In this exercise, the optimal solution for the primal problem was found to be \((x, y) = (13, 0)\). This means that 13 units of \(x\) and 0 units of \(y\) achieve the minimum value of the cost function \(C = 3x + 2y \).The optimality of this solution is confirmed by the final simplex tableau. Each step taken during the simplex iteration process is to ensure that the chosen values lead to the best outcome, whether it be minimizing cost or maximizing profit. The dual problem also achieves its solution at the same point, demonstrating the powerful nature of duality in confirming the solution's optimality with a cost \(Z = 13\) for the dual.

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Most popular questions from this chapter

Use the method of this section to solve each linear programming problem. $$ \begin{aligned} \text { Minimize } & C=x-2 y+z \\ \text { subject to } & x-2 y+3 z \leq 10 \\ 2 x+y-2 z & \leq 15 \\ & 2 x+y+3 z \leq 20 \\ & x \geq 0, y \geq 0, z \geq 0 \end{aligned} $$

Use the method of this section to solve each linear programming problem. $$ \begin{aligned} \text { Minimize } & C=3 x+2 y+z \\ \text { subject to } & x+2 y+z \leq 20 \\ & 3 x+y \quad \leq 30 \\ & 2 x+y+z=10 \\ x & \geq 0, y \geq 0, z & \geq 0 \end{aligned} $$

Solve each linear programming problem by the simplex method. $$ \begin{aligned} \text { Maximize } & P=2 x+6 y+6 z \\ \text { subject to } & 2 x+y+3 z \leq 10 \\ & 4 x+y+2 z \leq 56 \\ & 6 x+4 y+3 z \leq 126 \\ & 2 x+y+z \leq 32 \\ & x \geq 0, y \geq 0, z & \geq 0 \end{aligned} $$

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Natsano has at most \(\$ 50,000\) to invest in the common stocks of two companies. He estimates that an investment in company A will yield a return of \(10 \%\). whereas an investment in company \(\mathrm{B}\), which he feels is a riskier investment, will yield a return of \(20 \%\). If he decides that his investment in the stock of company \(\mathrm{A}\) is to exceed his investment in the stock of company B by at least \(\$ 20,000\), determine how much he should invest in the stock of each company in order to maximize the return on his investment.

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