Hi, I have a 2 part question, here it is.

There are 60 pupils in a year at school, they are divided randomly into 3 classes of 20 pupils each. Alice, Bob and Caroline are all in the school year.

Part 1 - What is the probability that Alice and Bob end up in the same class?

Part 2 - What is the probability that Alice, Bob and Caroline all end up in different classes?

I can work out the answer to part one methodically as 19/59, but have no idea where to start with part 2. Any help would be much appreciated.