There are 4 picture nails on a wall and 8 pictures to choose from.In how many ways can a picture be hung on all the nails?

Question

how do you solve quetions like this one?

Answer 1

There are indeed ₈C₄=70 ways to choose the four pictures, but then 4! or 24 ways to order them on the nails.

Total 70×24=1680 ways to hang the pictures.

Answer 2

C⁸  =   8 !       = 70      

           4! * 4 !

Answer 3

This relates to Statistics and it sounds like you would need some practice with it. I'd be more than happy to assist you in more depth if you're having a lot of difficulty with it.