Answer :

Let the terms of the G.P. be a, ar, ar2, ar3, … , arn-2, arn-1

Sum of a G.P. series is represented by the formula, , when r≠1. ‘Sn’ represents the sum of the G.P. series upto nth terms, ‘a’ represents the first term, ‘r’ represents the common ratio and ‘n’ represents the number of terms.

Thus, the sum of this G.P. series is

The odd terms of this series are a, ar2, ar4, … , arn-2

{since the number of terms of the G.P. series is even; the 2nd last term will be an odd term.}


No. of terms will be as we are splitting up the n terms into 2 equal parts of odd and even terms. { since the no. of terms is even, we have 2 equal groups of odd and even terms }

Sum of the odd terms

By the problem,

r +1 =5

⇒∴ r = 4

Thus, the common ratio (r) = 4

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses

The product of thRD Sharma - Mathematics

Express <imRS Aggarwal - Mathematics

If a, b, c are inRS Aggarwal - Mathematics

Express <imRS Aggarwal - Mathematics

Prove that RS Aggarwal - Mathematics

If a, b, c are inRS Aggarwal - Mathematics

The sum of n termRS Aggarwal - Mathematics

If a, b, c, d areRS Aggarwal - Mathematics

Evaluate :
RS Aggarwal - Mathematics

The first term ofRS Aggarwal - Mathematics