SOLUTION: What is the equation and solution to find how long it takes for an investment to double in value if it is invested at 8% compounded monthly?

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Question 4876: What is the equation and solution to find how long it takes for an investment to double in value if it is invested at 8% compounded monthly?
Answer by ichudov(507) About Me  (Show Source):
You can put this solution on YOUR website!
If you invested X dollars, after a year you would get X*1.08. After two years, you would have X%2A1.08%5E2. Generally, after Y years, you would have $1.08%5Ey.
So, the equation for doubling is answering the question, what is the time y that is needed for an investment of $1 to grow to $2?
Writing it in algebrese,
2=1%2A1.08%5Ey
The solution is to tale a log with base of 1.08 of both sides:
log%28+1.08%2C+2+%29+=+log%28+1.08%2C+1.08%5Ey+%29
since log%28+1.08%2C+1.08%5Ey%29+=+y, we have
+log%28+1.08%2C+2+%29+=+y+
that's your solution. Double check it, as always. Also please post your question in more appropriate category.