Q20 of 176 Page 20

A G.P. consists of an even number of terms. If the sum of all the terms is 5 times the sum of the terms occupying the odd places. Find the common ratio of the G.P.

Let there be n terms.


a, ar, ar2, ar3, ……………..arn - 2, arn - 1


The sum of a G.P.


Odd terms of the sequence are:


a, ar2, ar4……………..arn - 2


So sum of this series =


⇒


According to the given problem:


⇒


⇒


⇒ r + 1 = 5


⇒ r = 4.


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