Respuesta :

Let's consider first what equation we must use:

 ⇒ use Combination Formula ⇒ [tex]._{n} C_{r}=\frac{n!}{r!(n-r)!}[/tex]

      ⇒ where 'n'  is the total number of items and 'r'

      is the number of items to choose

Let's look at the problem:

  • total number of students: 18
  • number of students needed for debate: 4

Let's plug it in:

 [tex]\frac{18!}{4!*(18-4)!} =\frac{18!}{4!*14!} =\frac{18*17*16*15}{4*3*2*1} =18*17*2*5=3060[/tex]

Thus there are 3060 ways

Answer: 3060 ways

Hope that helps!