A person speeds 75% of his income. If his income increase by 20% and expenses increase by 15%, his saving will increase by :

Solution(By Examveda Team)

Let original income = Rs. 100
Then savings = Rs. 25 and expenditure = Rs. 75
New income = Rs. 120
New expenditure :
$$=$$ 115% of Rs. 75
$$\eqalign{ & = {\text{Rs}}{\text{. }}\left( {\frac{{115}}{{100}} \times 75} \right) \cr & = {\text{Rs}}{\text{. }}\frac{{345}}{4} \cr} $$
New saving :
. $$\eqalign{ & = {\text{Rs}}{\text{. }}\left( {120 - \frac{{345}}{4}} \right) \cr & = {\text{Rs}}{\text{. }}\frac{{135}}{4} \cr} $$
Increase in saving :
$$\eqalign{ & = {\text{Rs}}{\text{. }}\left( {\frac{{135}}{4} - 25} \right) \cr & = {\text{Rs}}{\text{. }}\frac{{35}}{4} \cr} $$
∴ Percentage increase :
$$\eqalign{ & = \left( {\frac{{35}}{4} \times \frac{1}{{25}} \times 100} \right)\% \cr & = 35\% \cr} $$