The least number of complete years in which a sum of money put out at 20% C.I. will be more than doubled is_________?

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The least number of complete years in which a sum of money put out at 20% C.I. will be more than doubled is_________?

A. 3
B. 4
C. 5
D. 6
Explanation:
P(1 + 20/100)n > 2P or (6/5)n > 2
Now, (6/5 * 6/5 * 6/5 * 6/5) > 2. So, n = 4 years.