In how many years will a sum of Rs. 800 at 10% per annum

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In how many years will a sum of Rs. 800 at 10% per annum compounded semi-annually become Rs. 926.10?

1. 2 1 years
  2
2. 3 years
3. 2 years
4. 1 1 years
  2

Correct Option: D

According to question ,
Rate = 10% Per annum = 5% per half year , Time = T years = 2T half years
We can find required answer with the help of given formula ,

∴ A = P		1 +	R		^T
			100

⇒ 926.10 = 800		1 +	5		^2T
			100

⇒	926.1	=		1 +	1		^2T
	800				20

⇒	9261	=		21		^2T
	8000			20

⇒		21		³	=		21		^2T
		20					20

Equating powers on both sides , we get

⇒ 2T = 3 ⇒ T =	3	years
	2