Find the sum up to 20 terms in the G.P 0.15, 0.015, 0.0015 .....

Solution:

The given G.P is

0.15, 0.015, 0.0015 .....

Here,

a = 0.15 and r = 0.015/0.15 = 0.1

It is known that

S_n = a (1 - rⁿ)/(1 - r)

Therefore,

Substituting n = 20,we get

S₂₀ = 0.15 (1 - (0.1)²⁰)/(1 - 0.1)

S₂₀ = 0.15/0.9 [(1 - (0.1)²⁰)]

= 1/6 [(1 - (0.1)²⁰)]

NCERT Solutions Class 11 Maths Chapter 9 Exercise 9.3 Question 7

Find the sum up to 20 terms in the G.P 0.15, 0.015, 0.0015 .....

Summary:

We found out that the sum up to 20 terms in the G.P represented by 0.15, 0.015, 0.0015 can be found out by the formula S_n = a (1 - rⁿ)/(1 - r) and the answer is 1/6 [(1 - (0.1)²⁰)]