Shashi had a certain amount of money. He invested $$\frac{2}{3}$$ of the total money in scheme A for 6 years and rest of the money he invested in scheme B for 2 years. Scheme A offers simple interest at a rate of 12% p.a. and scheme B offers compound interest ( compound annually) at a rate of 10% p.a. If the total interest obtained from both the schemes is Rs. 2750. What was the total amount invested by him in scheme A and scheme B together ? (Approximate value)
a) Rs. 4500
b) Rs. 4200
c) Rs. 4050
d) Rs. 5000

Answer: d
Explanation: Let the total sum of money invested by Shashi be Rs. x
In scheme A money invested at simple interest for 6 years at a rate of 12% p.a.
$$ \frac{2}{3}{\text{of }}x \times \frac{{12 \times 6}}{{100}} = \frac{{48x}}{{100}}….(i)$$
In scheme B money at compound interest for 2 year at a rate of 10% p.a.
$$\eqalign{ & \frac{x}{3}{\left( {1 + \frac{{10}}{{100}}} \right)^2} – \frac{x}{3} \cr & \Rightarrow \frac{x}{3}{\left( {1 + \frac{{10}}{{100}}} \right)^2} – \frac{x}{3} = \frac{{7x}}{{100}} \cr} $$
According to given information,
$$\eqalign{ & \frac{{48x}}{{100}} + \frac{{7x}}{{100}} = 2750 \cr & 55x = 2750 \times 100 \cr & x = \frac{{2750 \times 100}}{{55}} \cr & x = Rs.\,5000 \cr} $$