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

Answer

4

Explanation

`S_(2n)=5(t_(1)+t_(3)+t_(5)+….+n)`
`rArr(a(1-r^(2n)))/(1-r)=5xx(a{1-(r^(2))^(n)})/(1-r^(2))`
`rArr1=5/(1+r)`
or 1+r=5
or r=4