A student has to sell 2 books from a collection

leviattan0pi

leviattan0pi

Answered question

2021-12-01

A student has to sell 2 books from a collection of 6 math, 7 science, and 4 economics books. How many choices are possible if both books are to be on the same subject?

Answer & Explanation

Michele Grimsley

Michele Grimsley

Beginner2021-12-02Added 19 answers

There are (62) ways to choose 2 math textbooks from the 6 available.
Similarly, there are (72) ways to choose 2 science textbooks from 7 of them and (42) ways to choose 2 economics textbooks from 4 of them.
These choices ensure that the 2 textbooks are always from the same subject. Adding up these choices gives the no. of ways of selling two textbooks of the same subject.
(62)+(72)+(42)=42

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