If a certain sum of money doubles itself in 6 years, in how many years will it…

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If a certain sum of money doubles itself in 6 years, in how many years will it be three times at the same rate of simple interest?

  1. A.

    10 years

  2. B.

    19 years

  3. C.

    12 years

  4. D.

    33 years

Attempted by 6 students.

Show answer & explanation

Correct answer: C

Step-by-Step Solution

To find the time required for a sum to triple itself under simple interest, we can analyze the growth of the interest earned.

  1. Analyze the first scenario (doubling):

    • If a sum doubles, the Amount (A) becomes 2P (where P is the principal).

    • Simple Interest (SI) earned = Amount - Principal = 2P - P = P.

    • This interest (P) is earned in 6 years.

  2. Analyze the second scenario (tripling):

    • To triple the sum, the Amount (A) must become 3P.

    • Simple Interest (SI) required = Amount - Principal = 3P - P = 2P.

  3. Calculate the time required:

    • Since Simple Interest is directly proportional to time, we can set up a ratio:

    • (SI 1) / (Time 1) = (SI 2) / (Time 2)

    • P / 6 years = 2P / (Time 2)

    • Time 2 = (2P * 6 years) / P

    • Time 2 = 12 years.

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