SOLUTION: Find t10 and S10 for the arithmetic series in which t4 = 11.6 and t8 = 12.4.

Algebra ->  Sequences-and-series -> SOLUTION: Find t10 and S10 for the arithmetic series in which t4 = 11.6 and t8 = 12.4.       Log On


   

Question 1150466: Find t10 and S10 for the arithmetic series in which t4 = 11.6 and t8 = 12.4.
Answer by greenestamps(13209) About Me  (Show Source):
You can put this solution on YOUR website!


Given: t(4) = 11.6; t(8) = 12.4.

Let d be the common difference.

t%288%29+=+t%284%29%2B4d
12.4+=+11.6%2B4d
0.8+=+4d
d+=+0.2

Find t(10):

t%2810%29+=+t%288%29%2B2d+=+12.4%2B2%280.2%29+=+12.8

Find S(10):

t%281%29+=+t%284%29-3d+=+11.6-3%280.2%29+=+11

S%2810%29+=+10%28%28t%281%29%2Bt%2810%29%29%2F2%29+=+5%2811%2B12.8%29+=+5%2823.8%29+=+119