Ex 8.2, 7 - Chapter 8 Class 11 Sequences and Series
Last updated at Dec. 16, 2024 by Teachoo
Ex 8.2
Ex 8.2, 1
You are here
You are here
Chapter 8 Class 11 Sequences and Series
Serial order wise
Transcript
Ex 8.2,7 Find the sum to 20 terms in the geometric progression 0.15, 0.015, 0.0015 0.15, 0.015, 0.0015 We know that Sn = (a(1 ^ ))/(1 r) where Sn = sum of n terms of GP n is the number of terms a is the first term r is the common ratio First term a = 0.15 , Common ratio r = 0.015/0.15 ` = 15/1000 100/15 = 1/10 We know that Sum of n term = ( (1 ^ ))/(1 ) We need to find sum of 20 terms. S20 = ( (1 ^20))/(1 ) We need to find sum of 20 terms, we use the formula Sn = (a(1 ^ ))/(1 r) Putting a = 0.15, r = 0.1,n=20 S20 = (0.15(1 (0.1)20))/(1 0.1) S20 =(0.15(1 (0.1)20))/0.9 S20 = 1/6[ 1 (0.1)20] Hence, sum of 20 terms of GP is 1/6[ 1 (0.1)20]
