A sum of money amounts to ₹ 4,840 in 2 years and to ₹

A sum of money amounts to ₹ 4,840 in 2 years and to ₹ 5,324 in 3 years at compound interest compounded annually. The rate of interest per annum is :

Let the rate of interest be r% per annum,
According to the question,

4840 = P		1 +	r		²	..... (i)
			100

and 5324 = P		1 +	r		³	..... (ii)
			100

On dividing equation (ii) by equation (i), we have,

1 +	r	=	5324	= 1 +	484
	100		4840		4840

⇒	r	=	484
⇒	100	=	4840

⇒ r = 10%
Second Method to solve this question :
Here, b – a = 3 – 2 = 1 and B = Rs 5,324, A = 4,840

R% =		B	− 1		× 100%
		A

R% =		5324	− 1		× 100%
		4840

R% =		5324 − 4840		× 100%
		4840

R% =	484	× 100% = 10%
	4840