Old McDonald keeps 15 goats on his farm, among them a goat called Edna. One of the other goats is Edna's best friend. Unfortunately, another of them is her worst enemy. One day, Old McDonald decides to exercise the goats in three separate enclosures. Five randomly selected goats will be assigned to each enclosure. What is the probability that Edna will be assigned to the same group as her best friend, but not her worst enemy?
I tried doing 1*4/14*10/13. Is this the correct way to do this?