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(a) In all, there are = = 142506 different ways to select group of 5 persons from 30 persons.
The group of 5 youngest persons of 30 is the UNIQUE such group of 5 persons from 30, under given conditions.
So, the probability you are looking for is . ANSWER
(b) = .
Use your calculator.
(c) = = 28. ANSWER
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All these problems/questions are about 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.