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What is the difference between the sum of a Geometric Series, whose 1st. term is 1, common ratio 10% and the number of terms 100, and exactly this same Geometric Series, whose terms from 1 to 100 earned interest at 5% compounded annually for 100 years! Thanks for help

 Dec 21, 2016
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1) Using the well-known formula for the sum of geometric series: Sum=F x (1 - R^n) / (1 - R), we get:

 =137,796.12

 

2) For each term to get interest at 5%, will  have to sum them up on any good calculator, such as Wolfram/Alpha as follows: ∑(1.10^n)(1.05)^(99-n), from n=0 to 99

=$272,982.22. Here is the link:  http://www.wolframalpha.com/input/?i=%E2%88%91(1.10%5En)(1.05)%5E(99-n),+from+n%3D0+to+99

 

3) The difference between 2 and 1 above is:$272,982.22 - $137,796.12 =$135,186.10 interest only.

 Dec 22, 2016

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