How many terms of the G.P. 
are needed to give the sum 
?
Given:
Sum of GP 
∴ Common Ratio = r 
a = 3
To find: Number of terms = n.
Sum of GP for n terms = 
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
∴ n = 10.
17
How many terms of the G.P. are needed to give the sum ?
Given:
Sum of GP
∴ Common Ratio = r
a = 3
To find: Number of terms = n.
Sum of GP for n terms =
⇒
⇒
⇒
⇒
⇒
⇒
∴ n = 10.