SOLUTION: Find how long it takes a ​$1200 investment to earn ​$600 interest if it is invested at 5​% interest compounded quarterly.

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Question 1157482: Find how long it takes a ​$1200 investment to earn ​$600 interest if it is invested at 5​% interest compounded quarterly.
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


$600 interest means the original $1200 has grown to $1800.

If t is the number of years and the interest is 5% compounded quarterly, then

1800+=+1200%281%2B.05%2F4%29%5E%284t%29

Graph using a graphing calculator, or solve using logarithms....

1.5+=+1.0125%5E%284t%29%7D%7D%0D%0A%7B%7B%7Blog%28%281.5%29%29+=+4t%2Alog%28%281.0125%29%29
4t+=+log%28%281.5%29%29%2Flog%28%281.0125%29%29

You can finish....