Q. Find the sum of the first 6 terms of the following series, to the nearest integer.20,10,5,…Answer:
Identify type and ratio: Identify the type of series and the common ratio.The given series is geometric because each term is obtained by multiplying the previous term by a constant ratio.To find the common ratio r, we divide the second term by the first term.r=2010=0.5
Use formula for sum: Use the formula for the sum of the first n terms of a geometric series.The sum Sn of the first n terms of a geometric series is given by the formula:Sn=a×(1−rn)/(1−r), where a is the first term, r is the common ratio, and n is the number of terms.In this case, a=20, r=0.5, and n=6.
Calculate sum of terms: Calculate the sum of the first 6 terms.S6=20×(1−0.56)/(1−0.5)S6=20×(1−0.015625)/0.5S6=20×0.984375/0.5S6=19.6875/0.5S6=39.375Since we need to round to the nearest integer, the sum is approximately 39.