Carcass wrote:
Craig invited four friends to watch a TV show. He arranged 5 seats in a row. The number of ways he and his four friends can sit in the row is n. In how many of these ways can Craig sit in the middle?
(A) \(n\)
(B) \(\frac{n}{2}\)
(C) \(\frac{n}{3}\)
(D) \(\frac{n}{4}\)
(E) \(\frac{n}{5}\)
5! is n and is how many ways they can all sit and 4! is how many combinations there are with him in the middle.
Therefor 4! = (x)5!
4!/5! = 1/5 = x
substitute x =1/5 and 5! = n into the equation to see that n/5 indeed the answer (e).