Multiple choice

For how many years should Rs. $1200$ be invested at $10\%$ p.a. in order to earn the same simple interest as is earned by investing Rs. $1800$ at $12\%$ p.a. for $5$ years ?

  1. $9$
  2. $10$
  3. $12$
  4. $11$
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A Correct answer
Explanation

Simple Interest = (P * R * T) / 100. Interest 1 = (1200 * 10 * T) / 100 = 120T. Interest 2 = (1800 * 12 * 5) / 100 = 1080. Setting 120T = 1080 gives T = 9.

AI explanation

Using the simple interest formula, the interest earned by investing 1800 at 12% for 5 years is 1800 multiplied by 12 multiplied by 5 divided by 100, which equals 1080. To earn the same interest from 1200 at 10%, we set 1200 multiplied by 10 multiplied by T divided by 100 equal to 1080. Solving for T gives 120 times T equals 1080, which means the required time is 9 years.

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