Multiple choice

Certain sum gets doubled in 2 years at compound interest. What is the minimum number of years required in which the sum should become at least 7 times?

  1. 5

  2. 6

  3. 7

  4. 8

  5. 4
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B Correct answer
Explanation

Sum doubles in 2 years. In 4 years, it becomes 4 times. In 6 years, it becomes 8 times. Since 8 is greater than 7, the minimum number of years is 6.

AI explanation

Using the compound interest growth formula, if a sum doubles in 2 years, it grows by a factor of 2 every 2 years. To become at least 7 times, we test multiples of 2 years: after 4 years the sum is 4 times, and after 6 years the sum is 8 times. Therefore, it requires a minimum of 6 years.

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