SOLUTION: There are 4 freshman, 6 sophomores, 7 juniors, and 3 seniors on a school field trip. Three students are needed to carry water bottle cases. How many different ways can these studen

Question 1116312: There are 4 freshman, 6 sophomores, 7 juniors, and 3 seniors on a school field trip. Three students are needed to carry water bottle cases. How many different ways can these students be selected if they must be all three freshman or all three juniors?
Answer by ikleyn(52780) (Show Source): You can put this solution on YOUR website!
.

The number of way to select 3 students from 4 + 6 + 7 + 3 = 20 students is   = 1140.


Of them, the number of favorable combinations is   +  = 4 + 35 = 39.


Therefore, the probability under the question is  this number   = 0.034 = 3.4%.

Solved.

In order to solve freely such problems, you need to know 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.

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