Question

Find the sum of money which increases by $\frac{1}{10}$th of itself every year and amounts to ₹ 450 in 5 years, if calculated as per simple interest formula.

• A. Rs. 100
• B. Rs. 150
• C. Rs. 300
• D. Rs. 400

Answer 1

The correct option is C

Rs. 300

Let P be the principle
R = rate of interest
T = time taken
A = amount

A = P + $\frac{P\times R\times T}{100}$

$A=P(1+\frac{R\times T}{100})$

$A=P\left[\frac{100+(R\times T)}{100}\right]$

$\therefore$ P $=\frac{100\times A}{100+(R\times T)}$

Interest is $10\%$. Amount is Rs. 450.

$=\frac{100\times 450}{100+(10\times 5)}=Rs.300$