.
(a) Seven items can be selected from 23 different items by ways
= = 245157 ways.
It is the number of COMBINATIONS in this case.
(b) In this case you are allowed to select only 7-3=4 items from 23-3 = 20 items.
It can be done by ways.
This time, calculate the value ON YOUR OWN.
Happy calculations (!)
Solved.
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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.
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