A sum of money becomes 1.331 times in 3 years as compound

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A sum of money becomes 1.331 times in 3 years as compound interest. The rate of interest is

1. 8%
2. 7.5%
3. 10%
4. 50%

Correct Option: C

As per the given in question ,
Time = 3 years , Rate = R%
Suppose principal = ₹ 1000 , then amount = ₹ 1331

∴ A = P		1 +	R		^T
			100

⇒ 1331 = 1000		1 +	R		³
			100

⇒	1331	=		1 +	R		³
	1000				100

⇒		11		³	=		1 +	R		³
		10						100

⇒ 1 +	R	=	11
	100		10

⇒	R	=	1
	100		10

⇒ R =	1	× 100 = 10%
	10

Second Method to solve this question :
Here, n = 1.331, t = 3 years
R% = (n^1/t − 1) × 100%
R% = [(1.331)^1/3 − 1] × 100%
R% =[1.1 − 1] × 100%
R% = 0.1 × 100% = 10%