I'm sure a lot of people have seen questions like this one. I've gotten half of it done, but I could use a hand with the other half.
A large box contains 10 pairs of shoes. If 6 shoes are selected at random, what is the probability of:
a) no complete pairs
b) exactly one complete pair
c) exactly two complete pairs
d) exactly three complete pairs
I could use a hand with the latter two.