Multiple choice

Some amount on simple interest becomes five times more in 20 years. In how much time, the same amount will become four times on same rate?

  1. 12 years

  2. 15 years

  3. 18 years

  4. 20 years
Reveal answer Fill a bubble to check yourself
B Correct answer
AI explanation

The interest earned is four times the principal (since the amount becomes five times), so 400P equals (P times R times 20) divided by 100, meaning the rate R is 20%. For the amount to become four times, the interest must be three times the principal, giving 300P equals (P times 20 times T) divided by 100. Solving for T, we get T equals (300 divided by 20), which is 15 years, so the required time is 15 years.

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