SOLUTION: In an arithmetic series t1 = 11/3 , t3 = 3. Find the value of n for which Sn = 20.

Question 1150465: In an arithmetic series t1 = 11/3 , t3 = 3. Find the value of n for which Sn = 20.
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

t(1) = 11/3; t(3) = 3 = 9/3.

Let d be the common difference.

There are two solutions to the problem: n = 8 and n = 15.

The sum of terms 1 through 8 is 20; then the sum of terms 9 through 15 is 0, so the sum of terms 1 through 15 is again 20.

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