Find the sum to 20 terms in the geometri | Class 11 Mathematics Chapter Sequence and Series, Sequence and Series NCERT Solutions

Question:

Find the sum to 20 terms in the geometric progression 0.15, 0.015, 0.0015 …

Answer:

The given G.P. is 0.15, 0.015, 0.00015, …

Here, a = 0.15 and r = fraction numerator 0.015 over denominator 0.15 end fraction equals 0.1

S subscript n space end subscript equals space fraction numerator a space open parentheses 1 minus r to the power of n close parentheses over denominator 1 minus r end fraction
s o
S subscript 20 space equals space fraction numerator 0.15 open square brackets 1 minus open parentheses 0.1 close parentheses to the power of 20 close square brackets over denominator 1 minus 0.1 end fraction
space space space space space space space space space equals space fraction numerator 0.15 over denominator 0.9 end fraction open square brackets 1 minus open parentheses 0.1 close parentheses to the power of 20 close square brackets
space space space space space space space space space equals space 15 over 90 space open square brackets 1 space minus space open parentheses 0.1 close parentheses to the power of 20 close square brackets
space space space space space space space space space equals space 1 over 6 open square brackets 1 minus open parentheses 0.1 to the power of 20 close parentheses close square brackets space

 


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Welcome to the NCERT Solutions for Class 11 Mathematics - Chapter . This page offers a step-by-step solution to the specific question from Excercise 3 , Question 7: Find the sum to 20 terms in the geometric progression 0.15, 0.015, 0.0015 …....