The principal would like to assemble a committee of 5 students from the 15-memberstudent council. How many different committees can be chosen?

Respuesta :

SOLUTION

The question involves combination since it only deals with the selection without arrangement.

Hence the formula to use is

[tex]^nC_r=\frac{n!}{(n-r)!r}[/tex]

For this question, we have

[tex]\begin{gathered} n=15,r=5 \\ ^nC_r=\frac{n!}{(n-r)!r} \\ \text{becomes } \\ ^{15}C_5=\frac{15!}{(15-5)!5!} \end{gathered}[/tex]

Simplifying the last expression we obtained

[tex]\begin{gathered} ^{15}C_5=\frac{15!}{10!5!} \\ =\frac{15\times14\times13\times12\times11\times10!}{10!\times5!} \\ =3003 \end{gathered}[/tex]

Therefore,

The number of committees to be chosen is 3003