Matrices - Application of Matrices

Matrices - Application of Matrices

Secondary 4

Four shops sell different brands of running shoes: Mizuho, Azizs, New Ballast and Nikuu. The table below shows the number of shoes sold by the four shops in a particular week.

ShopMizuhoAzizsNew BallastNikuu
Running Sports\(10\)\(12\)\(15\)\(8\)
Real Runners\(5\)\(11\)\(8\)\(17\)
Run Fast\(16\)\(4\)\(7\)\(6\)
Strong Runners\(6\)\(8\)\(4\)\(11\)
  1. Represent the information given in the table above by a \(4 \times 4\) matrix \(S\).
  2. Mizuho shoes are sold at \(\$160\) each, Azizs shoes at \(\$120\) each, New Ballast shoes at \(\$120\) each and Nikuu shoes at \(\$140\) each. Write down a \(4 \times 1\) matrix \(P\) to represent the selling prices, in dollars, of the different brands of shoes.
    1. Find \(SP\).
    2. Explain what the elements in the matrix \(SP\) represent.
    3. It is given that \(T = \begin{pmatrix} 1 \\ 1 \\ 1 \\ 1 \end{pmatrix}\). Evaluate \(ST\) and explain what the elements of \(ST\) represent.

Solution:

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Answer:(a) \(\begin{pmatrix}10&12&15&8\\5&11&8&17\\16&4&7&6\\6&8&4&11\end{pmatrix}\); (b) \(\begin{pmatrix}160\\120\\120\\140\end{pmatrix}\); (c)(i) \(\begin{pmatrix}5960\\5460\\4720\\3940\end{pmatrix}\); (ii) weekly shop revenues in dollars; (iii) \(\begin{pmatrix}45\\41\\33\\29\end{pmatrix}\), weekly numbers of shoes sold per shop.

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