Shabana bought 16 dozen ball bens and sold them at a loss equal to S.P. of 8 ball pens. Find

(i) Number of pens bought $=16 \times 12=192$

Let the S. P of one pen be Rs. $x .$

Therefore, $S . P$ of 192 pens $=$ Rs. $192 x$

S. P of 8 pens $=$ Rs. $8 x$

It is given that $S . P$ of 8 pens is equal to the loss on selling 192 pens.

Therefore, loss $=$ Rs. $8 x$

C. P of 192 pens $=$ Rs. 576

So, loss $=$ C. P - S.P

$8 x=576-192 x$

$200 \mathrm{x}=576$

$x=\frac{576}{200}=2.88$

Therefore, loss $=8(2.88)=$ Rs. $23.04$

Loss $\%=\frac{\text { loss } \times 100}{\text { C.P }}$

$=\frac{23.04 \times 100}{576}$

$=4 \%$

(ii) S. P of 1 pen $=$ Rs. $2.88$

Therefore, S.P of 1 dozen pens $=12 x=12 \times 2.88$

$=$ Rs. $34.56$