SOLUTION: There is a stack of logs in the backyard. There are 15 logs in the 1st layer, 14 in the 2nd, 13 in the 3rd and so on with the last,layer having one log. The total number of logs is

Algebra ->  Sequences-and-series -> SOLUTION: There is a stack of logs in the backyard. There are 15 logs in the 1st layer, 14 in the 2nd, 13 in the 3rd and so on with the last,layer having one log. The total number of logs is      Log On


   

Question 1163856: There is a stack of logs in the backyard. There are 15 logs in the 1st layer, 14 in the 2nd, 13 in the 3rd and so on with the last,layer having one log. The total number of logs is

Answer by ikleyn(52788) About Me  (Show Source):
You can put this solution on YOUR website!
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. . . is the sum of the first n=15 natural numbers, which is  %28n%2A%28n%2B1%29%29%2F2 = %2816%2A15%29%2F2 = 8*15 = 120.    ANSWER

Solved.

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It is about the sum of the first n terms of an arithmetic progression.

For introductory lessons on arithmetic progressions see
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions
in this site.

Also,  you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Arithmetic progressions".


Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.