The sum of an infinite geometric series is 1,280, while the first term of the series is 160. What is the common ratio of the series?

asked Aug 17, 2018 14.1k views

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The sum is 160/(1-r)=1280 where r is the common ratio,
1/(1-r)=1280/160=8
Inverting we get 1-r=1/8, r=7/8.

Cheng Chen answered Aug 21, 2018

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