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A fisherman has 12 different trout flies. How many different selections of 3 flies each can he make?
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12*11*10 = 1320, if the order is important. (ordered sets, permutations).
= = 2*11*10 = 220, if the order is not important. (unordered sets, combinations).
Solved.
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On Combinations and Permutations, see introductory lessons
- Introduction to Permutations
- PROOF of the formula on the number of Permutations
- Simple and simplest problems on permutations
- Introduction to Combinations
- PROOF of the formula on the number of Combinations
- Problems on 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.