Question

If a discount of $10\%$ is given on the marked price of a book, the publisher gains $20\%$. If the discount is increased to $15\%$, the gain is __________.

• A. $16\frac{2}{3}\%$
• B. $13\frac{1}{3}\%$
• C. $15\frac{1}{6}\%$
• D. None of these

Answer 1

The correct option is B $13\frac{1}{3}\%$

Let $CP=100$

Marked Price$=x$.

$SP=100+20\%of100=120$

$10\%$ discount was given on SP.

$SP=x-10\%\text{of}x$

$120=x-\frac{10x}{100}$

$120=\frac{9x}{10}$

$x=\frac{1200}{9}=133.33$

$MP=133.33$

If $15\%$ discount was given, then

$SP=133.33-15$

$SP=113.33$

$Gain=133.33-100$

$\%Gain=13.33\%$

$=13\frac{1}{3}\%$