SOLUTION: How many 3-element subsets does the set {1, 2, 3, 4, 5, 6, 7} have?

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Question 1092757: How many 3-element subsets does the set {1, 2, 3, 4, 5, 6, 7} have?
Answer by ikleyn(52790) About Me  (Show Source):
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The number of 3-element subsets in this 7-elements finite set is equal 


to the number of combination of 7 items taken 3 at a time


C%5B7%5D%5E3 = %287%2A6%2A5%29%2F%281%2A2%2A3%29 = 7*5 = 35.


Each such subset is this kind of combinations.


On Combinations see the lessons
    - Introduction to Combinations
    - PROOF of the formula on the number of Combinations
    - Problems on Combinations
    - OVERVIEW of lessons on Permutations and Combinations
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  "Combinatorics: Combinations and permutations".


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.