Respuesta :
He can make 10 different types of boards.
This is a combination of 5 objects chosen 3 at a time:
[tex]_nC_r=\frac{n!}{r!(n-r)!} \\ \\_5C_3=\frac{5!}{3!2!}=\frac{120}{12}=10[/tex]
This is a combination of 5 objects chosen 3 at a time:
[tex]_nC_r=\frac{n!}{r!(n-r)!} \\ \\_5C_3=\frac{5!}{3!2!}=\frac{120}{12}=10[/tex]
