Question

After receiving two successive raises Hrash's salary became $\frac{15}{8}$ times of his initial salary. By how much percent was the salary raised the first time if the second raise was twice as much as high (in percent) as the first ?

• A. $15\%$
• B. $20\%$
• C. $25\%$
• D. $30\%$

Answer 1

Answer: (C)

$25\%$

Let initial salary was Rs. $100$
After two raise it become $\frac{15}{8}$ i.e. $\frac{(15\times 100)}{8}=$ Rs. $187.5$
Raise $=187.5-100=87.5$
Using formula,
[( first raise + second raise) + (first raise * 2nd raise) / 100] = 87.5
$x+2x+\frac{\left(2x^2\right)}{100}=87.53$
$300x+2x^2=8750$
$x^2+150x=4375$
$x^2+150x-4375=0$
$x^2+175x-25x-4375=0$
$x=-175,25$ .....(Negative value is not possible)
So, $x=25\%$
Second raise was $2x=2\times 25=50\%$.