When we need to know how many combinations we can get from a number of objects and the order is relevant, one could use "permutations". The formula is:
[tex]k=nPr=\frac{n!}{(n-r)!}[/tex]Where k is the number of permutations, n is the total number of objects and r is the number of those you want to choose. In this exercise, we set n=9, r=4.
[tex]k=\frac{9!}{(9-4)!}=\frac{9!}{5!}=3024[/tex]Therefore, we could choose president, vice-president, secretary, and treasurer in 3024 ways from a club of 9 people. Answer B.
