Question

A fountain pen is bought in Rs. 20. For how much it be sold so as to gain $10 \%$?

Answer 1

Let the C.P. $=$ Rs. 100

$\begin{aligned}\therefore \text { S.P. } &=100+10 \% \text { of } 100 \\&=100+10=\text { Rs. } 110\end{aligned}$

$\because$ When the C.P. is Rs. 100 , then the S.P. = Rs. 110

$\therefore \quad$ When the C.P. is Re. 1 , then the

$\text { S.P. }=\text { Rs. } \frac{110}{100}$

$\therefore$ When the C.P. is Rs. 20 , then

$\text { the S.P. }=\text { Rs. } \frac{110}{100} \times 20$

$\text { = Rs. } 22 \text {; Ans. }$