- Understand how to add and subtract matrices
- Figure out how to multiply a matrix by a number (scalar) to change its scale
- Learn to multiply two matrices together to find a new matrix
Using Matrices in Real-World Problems
Lab [latex]A[/latex] | Lab [latex]B[/latex] | |
---|---|---|
Computers | [latex]15[/latex] | [latex]27[/latex] |
Computer Tables | [latex]16[/latex] | [latex]34[/latex] |
Chairs | [latex]16[/latex] | [latex]34[/latex] |
Convert the data to a matrix and find the inventory for 2014.
Computer inventory in fall 2013:
[latex]{C}_{2013}=\left[\begin{array}{c}15\\ 16\\ 16\end{array}\begin{array}{c}27\\ 34\\ 34\end{array}\right][/latex]
To calculate how much computer equipment will be needed in 2014, we multiply all entries in matrix [latex]C[/latex] by [latex]0.15[/latex].
[latex]\left(0.15\right){C}_{2013}=\left[\begin{array}{c}\left(0.15\right)15\\ \left(0.15\right)16\\ \left(0.15\right)16\end{array}\begin{array}{c}\left(0.15\right)27\\ \left(0.15\right)34\\ \left(0.15\right)34\end{array}\right]=\left[\begin{array}{c}2.25\\ 2.4\\ 2.4\end{array}\begin{array}{c}4.05\\ 5.1\\ 5.1\end{array}\right][/latex]
We must round up to the next integer, so the amount of new equipment needed is
[latex]\left[\begin{array}{c}3\\ 3\\ 3\end{array}\begin{array}{c}5\\ 6\\ 6\end{array}\right][/latex]
Adding the two matrices as shown below, we see the new inventory amounts.
[latex]\left[\begin{array}{c}15\\ 16\\ 16\end{array}\begin{array}{c}27\\ 34\\ 34\end{array}\right]+\left[\begin{array}{c}3\\ 3\\ 3\end{array}\begin{array}{c}5\\ 6\\ 6\end{array}\right]=\left[\begin{array}{c}18\\ 19\\ 19\end{array}\begin{array}{c}32\\ 40\\ 40\end{array}\right][/latex]
This means
[latex]{C}_{2014}=\left[\begin{array}{c}18\\ 19\\ 19\end{array}\begin{array}{c}32\\ 40\\ 40\end{array}\right][/latex]
Thus, Lab A will have [latex]18[/latex] computers, [latex]19[/latex] computer tables, and [latex]19[/latex] chairs; Lab B will have [latex]32[/latex] computers, [latex]40[/latex] computer tables, and [latex]40[/latex] chairs.
Wildcats | Mud Cats | |
---|---|---|
Goals | [latex]6[/latex] | [latex]10[/latex] |
Balls | [latex]30[/latex] | [latex]24[/latex] |
Jerseys | [latex]14[/latex] | [latex]20[/latex] |
We are also given the prices of the equipment, as shown in the table below.
Goal | [latex]$300[/latex] |
Ball | [latex]$10[/latex] |
Jersey | [latex]$30[/latex] |
How can we find the total cost for the equipment needed for each team?