Question

A sum of money doubles itself in 4 years in how many years it will be 5 times?

A 16 years Correct Answer Incorrect Answer
B 14 years Correct Answer Incorrect Answer
C 10 years Correct Answer Incorrect Answer
D 24 years Correct Answer Incorrect Answer
E None of these 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×4)/100) => 200 =100 + R× 4 => 100 =R× 4 => R = 25% According to the question, =>5P = P + (P×25×T)/100) => T = 16 years

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