Multiple choice

A sum becomes three times itself at compound interest in eight years. In how many years will the sum become twenty seven times itself?

  1. 24

  2. 20

  3. 18

  4. 10
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Compound interest: A = P(1+r/100)^t. 3P = P(1+r/100)^8. We want 27P = P(1+r/100)^t. 27 = 3^3. So (1+r/100)^t = ((1+r/100)^8)^3 = (1+r/100)^24. t = 24.

AI explanation

The sum becomes 3 times itself in 8 years, meaning it multiplies by 3 every 8 years. To become 27 times itself, the sum must undergo 3 such triplings, because 3^3 equals 27. Multiplying the 8 years by 3 gives the total time of 24 years.

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