Question

The bookshop of a particular school has 10 dozen chemistry books, 8 dozen physics books and 10 dozen economics books. Their selling prices are ₹ 80, ₹ 60, ₹ 40 each respectively. Find the total amount the bookshop will receive from selling all the books, using matrix algebra.

Answer 1

Let the number of books be represented by matrix A of order 1 x 3 as shown below :
A = [10 dozen 8 dozen 10 dozen]
= [120 96 120].
The cost of each book of chemistry, physics and economics are ₹ 80, ₹ 60 and ₹ 40 respectively. They are represented by the matrix R of order 3 x 1, i.e.,
R = \(\left[\begin{array}{l} 80 \\ 60 \\ 40 \end{array}\right]\)
Total amount (in ₹) received by selling all the books is given
AR = [120 96 120] \(\left[\begin{array}{l} 80 \\ 60 \\ 40 \end{array}\right]\)
= [120 x 80 + 96 x 60 + 120 x 40]
= [9600 + 5760 + 4800]
= [20160].
∴ Total amount received = ₹ 20160.