Question:
Tick (✓) the correct answer:
On selling 100 pencils a man gains the selling price of 20 pencils. His gain per cent is
(a) 20%
(b) 25%
(c) $22 \frac{1}{2} \%$
(d) $16 \frac{2}{3} \%$
Solution:
(b) 25%
Let the SP of 100 pens be Rs $x$.
SP of 1 pen $=$ Rs $\frac{x}{100}$
Profit $=$ Rs $\frac{20 x}{100}$
$=\mathrm{Rs} \frac{x}{5}$
Now, $\mathrm{CP}=x-\frac{x}{5}$
$=\frac{4 x}{5}$
$\therefore$ Gain percentage $=\frac{\frac{x}{5}}{\frac{5 x}{5}} \times 100$
= 25%