SOLUTION: Find the sum of following series. 100, 93,86,79......................up to 20 terms

Algebra.Com
Question 1048189: Find the sum of following series.
100, 93,86,79......................up to 20 terms



Answer by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
n = 20; a1 = 93 d = -7
a20=a1*-7(n-1)=100+(19)(7)
=100+(19)(-7)=-33
Sn=n(a1+an)/2
=20(100-33)/2=-20(67)/2=10*67=670

RELATED QUESTIONS

79, 84, 79, 93, 60, 86, 80 Find the mean, median, and mode of Sean’s grades. Round to (answered by swincher4391)
In a geometric series, the 9th term is equal to 8 times the 6th term, while the sum of... (answered by robertb)
Can someone please help me? 1. Find the sum of each arithmetic series. Part I: -15 + -3 (answered by josgarithmetic)
Find the sum of the first 9 terms of the following series, to the nearest integer.... (answered by oscargut)
Find the sum of the first 6 terms of the following series, to the nearest integer.... (answered by 2897696,josgarithmetic)
The sum of first 20 terms of the series... (answered by satyareddy22)
Given the first four terms and the number of terms in the series, what is the sum of the... (answered by Boreal,ikleyn)
find the sum of he first 20 terms of the airthmetic series... (answered by Nate)
find the sum of the first 20 terms in the series... (answered by josgarithmetic,srinivas.g,MathTherapy)