A sum of ₹ 8000 will amount to ₹ 8820 in 2 years if

A sum of ₹ 8000 will amount to ₹ 8820 in 2 years if the interest is calculated every year. The rate of compound interest is

Here , Principal ( P ) = ₹ 8,000 , Amount ( A ) = ₹ 8820 , Rate ( R ) = r% , Time = 2 years
If the rate of C.I. be r% per annum, then

A = P		1 +	R		^T
			100

⇒ 8820 = 8000		1 +	r		²
			100

⇒	8820	=		1 +	r		²
	8000				100

⇒	441	=		21		²	=		1 +	r		²
	400			20						100

⇒ 1 +	r	=	21
	100		20

⇒	r	=	21	− 1 =	1
	100		20		20

⇒ r =	1	× 100
	20

∴ r = 5% per annum