Krish C. answered 08/01/20
Highly-Rated Mathematics Tutor
Consider the initial investment as x
We want the final amount to be 3x
Applying the compound interest formula
Amount = (Initial Amount)*(1+Rate)*(1+Rate)*(1+Rate) (multiply rate as many years to be interested)
So let the time be n years
We have, 3x = x*(1+0.04)n
i.e. 3 = 1.04n
Taking log to the base 1.04 on both sides, log1.043 = log1.041.04n
By the rules of logarithm, log1.043 = n*log1.041.04 = n*1 = n
Now you can either put it directly into your calculator and get
n = log1.043 = 28.011 years
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