High School

A bookshelf has room for four more books. Cindy has eight books that may be placed on the shelf. In how many ways can the books be placed?

A. 70
B. 32
C. 1680
D. 3125
E. 120

Answer :

Final answer:

The question is about combinatorial mathematics, more specifically combinations. The problem is to determine the number of ways 4 books can be selected from a set of 8 to be placed on a shelf. Using the mathematical formula for combinations (nCr = n! / [(n-r)! * r!]), we find there are 70 ways to place the books.

Explanation:

The subject of the question is combinatorial mathematics. Specifically, this is a problem of combinations. In this case, we have 8 books and we want to place 4 of them on a bookshelf. The order in which the books are placed does not matter in this context, only the selection of books. So, we simply need to calculate the number of ways to choose 4 books from 8, which is represented mathematically as the combination of 8 choose 4.

The formula for determining the combination of n items taken r at a time is:

nCr = n! / [(n-r)! * r!]

where 'n' is the total number of items; 'r' is the number of items to choose; 'nCr' represents the combination; '!' means factorial, which signifies a descending multiplication of integers from n to 1.

Applying this to the given question, we have:
8C4 = 8! / [(8-4)! * 4!], which simplifies to 8C4 = 70. Therefore, there are 70 ways the books can be placed on the bookshelf.

Learn more about combinations here:

https://brainly.com/question/24703398

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