A person's salary is decreased by steps of 20%, 15% and 10%. Approximately by what percent should the reduced salary be increases so as to get back the original salary ?

Solution(By Examveda Team)

Let original salary = Rs. 100
New salary :
90% of 85% of 80% of Rs. 100
$$\eqalign{ & = {\text{Rs}}{\text{.}}\left( {\frac{{90}}{{100}} \times \frac{{85}}{{100}} \times \frac{{80}}{{100}} \times 100} \right) \cr & = {\text{Rs}}{\text{.}}\frac{{306}}{5} \cr} $$
Increase on $$\frac{{306}}{5}$$ :
= $$\left( {100 - \frac{{306}}{5}} \right)$$
= $$\frac{194}{5}$$
Increase on 100 :
$$\eqalign{ & = \left( {\frac{{194}}{5} \times \frac{5}{{306}} \times 100} \right)\% \cr & = \frac{{9700}}{{153}}\% . \cr & = 63.39 \approx 63\% \cr} $$