Question

    A sum of money doubles itself at the compound interest x

    in 10 years. In how many years it will be four times at the same compound interest? 
    A 15 Correct Answer Incorrect Answer
    B 20 Correct Answer Incorrect Answer
    C 25 Correct Answer Incorrect Answer
    D 30 Correct Answer Incorrect Answer

    Solution

    ATQ, Given: Money doubles in 10 years at compound interest. We use the formula = 2 = (1+r) ¹⁰ Now, we need to find when the money becomes 4 times 4=(1+r)ᵗ Since 4 = 2², we substitute 2 = (1+r) ¹⁰ :- 4=(1+r) ²⁰  So, t = 20 years. Hence, the money will become 4 times in 20 years.

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