Question

Ram Lal invested a certain amount for three years, under compound interest compounded annually and received Rs.17820. If he had invested the same amount for six years at the same rate of interest compounded annually, he would have received Rs.49410. What amount (in Rs.) did he invest?

• A. 7520
• B. 4425
• C. 7892
• D. 6427
• E. 6500

Answer 1

The correct option is D 6427

Let the sum be P and the interest rate be r.

Then after ‘n’ years $A=P(1+\frac{r}{100}{)}^n=P{R}^{n}whereR=1+\frac{r}{100}$

Now, $17820=P{R}^3,49410=P{R}^6$

$R^3=\frac{49410}{17820}$

So, $P=\frac{17820\times 17820}{49410}$ =Rs.6427