Asked by Ana :)

a length of 200 cm is divided into 25 sections whose lengths are in A.P.given that the sum of the length of the 3 smallest sections is 4.2,the length of the larger section is?
please help ...
Answered by Steve
just use the formulas you know, and write down the facts as given:

S25 = 25/2 (2a+24d) = 200
S3 = 3/2 (2a+2d) = 4.2
Solve those two equations, and you get
a = 4/5
d = 3/5

"larger" indicates only two items. I assume you mean the "largest" term, which is

T25 = a+24d = 4/5 + 24*3/5 = 76/5 = 15.2
Answered by Anonymous
what year is this question from?
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