A math conference is presenting a lecture series with six different lectures. If Dr. Smith's lecture depends on Dr. Jones Lecture, so that Dr. Smith must be scheduled at some time after Dr. Jones, in how many orders can six lectures be scheduled?
Heres what I've come up with.
since the order matters, it must be a permutation.
after this, I really don't know how to proceed.
The order doesn't really matter, except for Dr. Jones and Dr. Smith.
Hmmmm, this seems to be a case-work problem
Since Dr. Smith MUST be after Dr. Jones,
he can be the 2nd, 3rd, 4th, 5th, or 6th.
So try to find the amount of lectures for
then add em up. I think thats what you do.