Q.

An infinite G.P. has first term 'x' and sum '5', then x belongs to                 [2004]

1 x<-10  
2 -10<x<0  
3 0<x<10  
4 x>10  

Ans.

(3)

x1-r=5 ⇒ r=1-x5

Since G.P. contains infinite terms

∴ -1<r<1

⇒-1<1-x5<1 ⇒ -2<-x5<0

⇒-10<x<0 ⇒ 0<x5<2

∴   0<x<10