Question

A company makes 3 types of cable. Cable A requires 3 black, 3 white, and 2 red wires. B requires 1 black, 2 white, and 1 red. C requires 2 black, 1 white, and 2 red. Make a 3 x 3 matrix showing the wire requirements. Assign the cable types to the rows and the wire types to the columns.

A) [2 1 2 1 2 1 2 1 3].
B) [3 3 2 1 2 1 2 1 1].
C) [3 1 2 3 2 1 2 1 2].
D) [2 1 3 1 2 1 2 1 2].

Answer 1

The answer is (B) but with 2 as the last item in the matrix, instead of 1.

Explanation:

The grand topic is MATRICES.

In Matrices, there are rules to follow when creating a matrix - which is a 'row by column' arrangement of objects or figures.

Rule 1: Identify your rows and columns.

What is a row? A row is a 'left to right' arrangement of items; also called a horizontal arrangement of items. What is a column? A column is an 'up to down' arrangement of items; also called a vertical arrangement of items.

Rule 2: Start your arrangement by rows.

Before reaching the instruction in the question, I already arranged the data for cables on the rows and the data for wire colors on the columns. You should follow this rule always; from the first information given in the question.

Rule 3: Nomenclature

This is the naming of a given matrix. In naming a matrix, consider the rows first before the columns. For example, a matrix with three rows and four columns with be called a 3 by 4 matrix and not a 4 by 3 matrix. In the case of this question, there is an equal number of rows and columns, so even if you counted the columns first, it wouldn't be noticed. Nevertheless, always count the rows first.

Having arranged the figures in a 3 by 3 matrix,

The full data on Cable A appears on the first row. The full data on Cable B appears on the second row. The full data on Cable C appears on the third row.

The full data on Black wires appears on the first column. The full data on White wires appears on the second column. The full data on Red wires appears on the third column.

So the answer is
`\left[\begin{array}{ccc}3&3&2\\1&2&1\\2&1&2\end{array}\right]`

Kudos!