Question

After two successive rises, the salary became equal to 15/8 parts of the initial salary. By how many per cent was the salary raised first time if the second rise was twice as high (in per cent) as the first?

Answer 1

Let initial salary$=x$

First raised salary $\%=y$

Second raised salary $\%=2y$

As per problem,

$\frac{x(100+y)}{100}\times \left(\frac{100+2y}{100}\right)=\frac{15}{8}\times x$

$\Rightarrow (100+y)(100+2y)=\frac{15}{8}\times 100\times 100$

$\Rightarrow 2y^2+300y-8750=0$

$\Rightarrow y=25$

$\therefore$ First raised salary$=25\%$