SOLUTION: From 7 Algebra books and 6 Geometry books, in how many ways can one select 2 Algebra and 2 Geometry books to buy if all the said books are equally necessary?

Question 1178630: From 7 Algebra books and 6 Geometry books, in how many ways can one select 2 Algebra and 2 Geometry books to buy if all the said books are equally necessary?
Answer by ikleyn(52777) (Show Source): You can put this solution on YOUR website!
.


There are   =  = 7*3 = 21 ways to select 2 Algebra books from 7 Algebra books.


There are   =  = 3*5 = 15 ways to select 2 Geometry books from 6 Geometry books.


THEREFORE, there are   = 21*15 = 315 ways to make that selection, which is prescribed in the problem.

Solved, answered, explained and completed.

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This problem is to use two conceptions of Combinatorics.

One conception is Combinations.
The other conception is the Fundamental counting principle.

Learn about both these conceptions from these introductory lessons, provided to you in this site
    - Introduction to Combinations
    - PROOF of the formula on the number of Combinations
    - Problems on Combinations
    - Fundamental counting principle problems
    - 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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