# g.p.

The ratio of the fourth and 12th term of a g.p. With positive common ratio is 1:256. If the difference of two terms be 61.2, find the sum of 8 terms of this series.

1. ar^3/ar^11 = 1/r^8 = 1/2^8
so, r = 2

I expect you can take it from there...

posted by Steve

posted by MathMate
3. Thanks

posted by Warnar
4. I don't trust anyone who tries to impersonate me and can't even get my name right.

posted by Ms. Sue

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