Question

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

• A. Rs. $20,160$
• B. Rs. $20,150$
• C. Rs. $20,170$
• D. Rs. $20,180$

Answer 1

The correct option is A Rs. $20,160$

No. of chemistry books $=10$ dozen $=10\times 12=120$
No. of physics books $=8$ dozen $=8\times 12=96$
No. of Economics books $=10$ dozen $=10\times 12=120$

Now, S.P of $1$ chemistry book $=$ Rs. $80$
S.P of $1$ Physics book $=$ Rs. $60$
S.P. of $1$ economic book $=$ Rs. $40$

Total S.P. $=\left[\begin{array}{ccc}120& 96& 120\end{array}\right]\left[\begin{array}{c}80\\ 60\\ 40\end{array}\right]$

$=120\times 80+96\times 60+120\times 40$
$=9600+5760+4800$
$=$ Rs. $20160$