A man buys 13 pens for a rupee. How many pens should he sell for a rupee to earn a profit of 30%?
Answer & explanation
Correct answer: option 2
If a man buys 13 pens for a rupee,
CP of 1 pen = $\frac{1}{13}$
For the man to earn profit of 30%,
If CP = 100, profit = 30
SP = 100 + 30 = 130
The ratio of CP to SP will be 100 : 130
Here, C.P. = 100R = $\frac{1}{13}$
Hence,
SP = 130R = 130 x $\frac{1}{13 \times 100}$ = $\frac{1}{10}$
Thus, a total of 10 pens should be sold to earn a profit of 30%.