If $A$ is a matrix of order $3 \times 4$ and $B$ is of order $4 \times 5$, then the order of the product $AB$ is:
- $3 \times 4$
- $4 \times 5$
- $3 \times 5$
- $5 \times 3$
Show answer and solution
Correct answer: C. $3 \times 5$
The product $A_{m \times n} \cdot B_{n \times p}$ is defined when the number of columns of $A$ equals the number of rows of $B$ ($n = 4$ here).
The result has order $m \times p = 3 \times 5$.