SOLUTION: how many years would it take to double $100 if it earned interest at a rate of 8% per year?

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Question 220267: how many years would it take to double $100 if it earned interest at a rate of 8% per year?
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
100%2A%281.08%29%5Ex+=+200
log%28%28100%2A1.08%29%5Ex%29+=+log%28%28200%29%29
This becomes:
log%28%28100%29%29+%2B+x%2Alog%28%281.08%29%29+=+log%28%28200%29%29
This becomes:
x+=+%28log%28%28200%29%29+-+log%28%28100%29%29%29%2Flog%28%281.08%29%29
This becomes:
x = 9.006468342
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to prove this is true, substitute in original equation to get:
100%2A%281.08%29%5E9.006468342+=+200
This becomes:
200 = 200 confirming the answer of x = 9.006468342 is good.
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It would take 9.006468342 years to double your money at 8% compounded yearly.
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