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There are 8 books on a shelf. If 3 books are chosen at random, how many different groups of3 books could be chosen? Determine if it is permutation or combination then solve.B). 28A). 19C). 56D). 65

Sagot :

Step 1:

The permutation is the number of different arrangement which can be made by picking r number of things from the available n things. The combination is the number of different groups of r objects each, which can be formed from the available n objects.

Permutation represent arrangement

Combination represent selection

Step 2:

The question is combination because its involved chosen or selection.

Step 3:

Number of ways of selecting 3 books from 8 books

n = 8 and r = 3

[tex]\begin{gathered} ^{}^{}Numberofwaysofselectingrobjectsoutofnobjects=^nC_r \\ =\text{ }\frac{n!}{(n-r)!r!} \\ =\text{ }\frac{8!}{(8-3)!3!} \\ =\text{ }\frac{8!}{5!3!} \\ =\text{ }\frac{8\times7\times6\times5!}{5!\times3\times2\times1} \\ \text{Cancel out common factors} \\ =\text{ }\frac{8\times7\times6}{6} \\ =\text{ 56 ways} \end{gathered}[/tex]

Final answer

Option C 56