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We have 9 pens, of which 5 are green ink, 3 are red ink, and 1 is black. If we put the pens in a line, how many arrangements are possible

Sagot :

Answer:

504 arrangements are possible

Step-by-step explanation:

Arrangements of n elements:

The number of arrangements of n elements is given by:

[tex]A_{n} = n![/tex]

Arrangements of n elements, divided into groups:

The number of arrangements of n elements, divided into groups of [tex]n_1, n_2,...,n_n[/tex] elements is given by:

[tex]A_{n}^{n_1,n_2,...,n_n} = \frac{n!}{n_1!n_2!...n_n!}[/tex]

In this case:

9 pens, into groups of 5, 3 and 1. So

[tex]A_{9}^{5,3,1} = \frac{9!}{5!3!1!} = 504[/tex]

504 arrangements are possible