The answer relies on whether the balls are different or not.
If they are not, which is almost certainly what is intended.
If they are, the perceptive is a bit different. Your
expression gives the likelihood that a particular set of j balls
goes into the last urn and the other n−j balls into the other urns.
But there are (nj) different possible sets of j balls, and each of
them the same probability of being the last insides of the last urn, so the
total probability of completing up with exactly j balls in the last
urn is if the balls are different.
See attached file for the answer.
So there are 12 spaces right. In first blank u have a choice to fill any of the alphabet .(first twelve alphabets) <span>and it goes down to just 1 letter in the last space. but do i just multiply them.
hope dis helps</span>
Cut 5 equal sections from a 2 foot long ribbond