Multiple choice

If a certain sum of money doubles in 3 years, in how many years will it become 8 times at compound interest?

  1. 27 yrs

  2. 21 yrs

  3. 12 yrs

  4. 9 yrs
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D Correct answer
Explanation

In compound interest, if a sum becomes 2 times in 3 years, it becomes 2^n times in 3*n years. For 8 times, 8 = 2^3, so time = 3 * 3 = 9 years.

AI explanation

When a sum doubles, the multiplication factor is 2. To become 8 times, the required multiplication factor is 8, which can be written as 2^3. Since the sum doubles in 3 years, it will take 3 multiplied by 3 years to become 8 times. The sum will become 8 times in 9 years.

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