Find the minimum number of complete years in which a sum of money put at 20% compound interest will be more than doubled.

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answer is A.

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Detailed Solution

Concept-
Assume that a sum of money (let's say P) invested for n full years at 20 percent compound interest will increase by more than double. The total amount after n years can then be determined using the compound interest formula. This sum will be equal to twice the principle, as stated in the question. Create an equation, then get the value of n.
If the initial amount is P, the annual compound interest rate is R %, and the number of years is n, then
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Let's assume that a sum of money (let's say P) invested at 20% compound interest will more than double in n full years.
Therefore,
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Taking log ,
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Hence, option 1 is the correct answer.

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