We have 7 teachers and we will select groups of 4.
We have to find how many ways we can select them.
As the order does not matter, this is a combination of 7 into 4.
We can then calculate it as:
[tex]\begin{gathered} C(n,r)=\frac{n!}{r!(n-r)!} \\ C(7,4)=\frac{7!}{4!3!}=\frac{5040}{24*6}=\frac{5040}{144}=35 \end{gathered}[/tex]Answer: we can select them in 35 different ways.
