Question

The bookshop of a particular school has 10 dozen Chemistry books, 8 dozen Physics books, 10 dozen Economics books. Their selling prices are $₹ 80, ₹ 60$ and $₹ 40$ each respectively. The total amount, the bookshop will receive from selling all the books using matrix algebra, is

• A. ₹ 21160
• B. ₹ 20610
• C. ₹ 26100
• D. ₹ 20160

Answer 1

Answer: (D)

Sirice, the boukstiop of a parlicular schoul has 10 dozen Chemistry books, 8 dozen Physics books, 10 dozen Economics books. Therefore, the matrix $A$ representing total number of each books is given by

Also, the selling price of each book is represented by the matrix
$B=\begin{bmatrix}80 \\60 \\40\end{bmatrix}$
Amount received by the bookseller on selling all the types of books can be computed by evaluating the product $A B$.
Now, $\quad A B=\begin{bmatrix}120 & 96 & 120\end{bmatrix}\begin{bmatrix}{l}80 \\ 60 \\ 40\end{bmatrix}$
$ =[120 \times 80+96 \times 60+120 \times 40]$
$ -[9600+5760+4800]$
$ \text { - [20160] } $
$\therefore$ Amount received by the bookseller is ₹ 20160 .