Answer:
220 possible ways
Step-by-step explanation:
Given
[tex]n = 12[/tex] --- people
[tex]r = 3[/tex] -- posts [tex](President, Vice\ President\ and\ Secretary)[/tex]
Required
Determine the number of selection
Since there is no condition attached, the number of selection is:
[tex]Selection = ^nC_r[/tex]
Substitute values for n and r
[tex]Selection = ^{12}C_3[/tex]
Apply combination formula
[tex]Selection = \frac{12!}{(12-3)!3!}[/tex]
[tex]Selection = \frac{12!}{9!3!}[/tex]
[tex]Selection = \frac{12*11*10*9!}{9!*3*2*1}[/tex]
[tex]Selection = \frac{12*11*10}{6}[/tex]
[tex]Selection = \frac{1320}{6}[/tex]
[tex]Selection = 220[/tex]
Hence, there are 220 possible ways