SOLUTION: How quickly will money triple if it is invested at 7% interest compounded continuously?

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Question 1138321: How quickly will money triple if it is invested at 7% interest compounded continuously?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
The compound interest formula is:

A+=+Pe%5E%28rt%29

Where A is the current value, P is the initial investment, r is the rate, and t is time.

If an investment triples, that means A is currently equal to 3%2AP

Your interest rate is r=7%, or, r=0.07

So

3P+=+Pe%5E%280.07t%29....simplify, both sides divide by P

3+=+e%5E%280.07t%29......take natural logarithm

ln%283%29+=ln%28+e%5E0.07t%29

ln%283%29+=+0.07t%2Aln%28+e%29

0.07t=ln%283%29+%2F++ln%28+e%29......ln%28+e%29=1

0.07t=ln%283%29

t+=+ln%283%29%2F0.07

t+=15.7 years