Solving Real-World Systems Using Matrices

00:00 10 marks

  • Exam Style - Paper 3
  • HL
  • Tier 5
  • Real-world applications
  • Systems of linear equations
  • Row reduction
  • Matrix inversion

A logistics company optimizes its delivery routes between three warehouses and three stores. The transportation of goods must meet specific demand requirements at each store, while respecting the supply capacities of each warehouse. Let \(a\), \(b\), and \(c\) represent the quantity of goods transported from warehouse 1, warehouse 2, and warehouse 3 respectively. The system of equations that models the transportation constraints is given by:

\(a + b + c = 100\) (Total demand constraint)
\(2a + 3b + c = 150\) (Store 1 specific demand)
\(a + 4b + 2c = 200\) (Store 2 specific demand)

Solve the following parts to determine the optimal quantities to transport from each warehouse.

Part a

4 minutes 3 marks

Question

Express the system of equations in matrix form \(AX = B\), where \(X = \begin{pmatrix} a \\ b \\ c \end{pmatrix}\). Identify and write down the coefficient matrix \(A\) and the constant matrix \(B\).



Hint Hint

Hint

Carefully extract the coefficients of \(a\), \(b\), and \(c\) from each equation to form matrix \(A\), and the constants on the right side to form matrix \(B\).

  • Answer Answer

Complete Answer

\(A = \begin{pmatrix} 1 & 1 & 1 \\ 2 & 3 & 1 \\ 1 & 4 & 2 \end{pmatrix}\), \(B = \begin{pmatrix} 100 \\ 150 \\ 200 \end{pmatrix}\)

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Part b

5 minutes 4 marks

Question

Solve the matrix equation \(AX = B\) using a GDC or matrix methods to find the values of \(a\), \(b\), and \(c\). State your answers to three significant figures if necessary.



Hint Hint

Hint

To solve for \(X\), you can compute the inverse of matrix \(A\) and then calculate \(X = A^{-1}B\), or use row reduction on the augmented matrix \([A|B]\).

  • Answer Answer

Complete Answer

\(a = 25,\, b = 12.5,\, c = 62.5\)

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Part c

3 minutes 3 marks

Question

Interpret the values of \(a\), \(b\), and \(c\) in the context of the logistics company’s transportation network. What do these values signify for the company’s operations?



Hint Hint

Hint

Consider what \(a\), \(b\), and \(c\) represent in terms of quantities transported from each warehouse and how this allocation might affect logistics and resource distribution.

  • Answer Answer

Complete Answer

The solution indicates that the company should transport 25 units of goods from warehouse 1, 12.5 units from warehouse 2, and 62.5 units from warehouse 3 to meet the demand constraints. These quantities represent the optimal allocation from each warehouse under the given system of equations.

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