Question

    A sum of money doubles itself in 8 years in how many

    years it will be 5 times?
    A 24 years Correct Answer Incorrect Answer
    B 40 years Correct Answer Incorrect Answer
    C 32 years Correct Answer Incorrect Answer
    D 30 years Correct Answer Incorrect Answer

    Solution

    Sum of money doubles, means interest is same as principal amount, Let Principal = P So, SI = P Amount = P + SI = P + P = 2P => A = P + (PRT/100) => 2P = P + (P×R×8)/100) => 200 = 100 + R × 8 => 100 = R × 8 => R = 12.5% According to the question, => 5P = P + (P×12.5×T)/100) => T = 32 years

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