SOLUTION: In how many ways can 5 letters be chosen from{Q,R,S,T,U,V,W}, assuming that the order of the choices doesn't matter and that repeats are not allowed?

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Question 1143547: In how many ways can 5 letters be chosen from{Q,R,S,T,U,V,W}, assuming that the order of the choices doesn't matter and that repeats are not allowed?

Answer by ikleyn(52894) About Me  (Show Source):
You can put this solution on YOUR website!
.
This question might be equivalently re-formulated in this way:


    "How many subsets of 5 elements can be formed from 7 distinct elements {Q, R, S, T, U, V, W} ?"


The answer is  C%5B7%5D%5E5 = %287%2A6%29%2F%281%2A2%29 = 21 subsets.



Here  C%5B7%5D%5E5  is the symbol for the number of all combinations of 7 distinct elements taken 5 at a time.


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On Combinations,  see introductory 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.