Here's an interesting toy problem:

You have 20 people sitting around a table. You want to form a committee of 3 people.

What is the probability/chance that at least 2 of the people are sitting together? What is the general form of the approach to finding the answer for this one?

It's been 15 years since I've done stats and surely this is easier than I'm making it out to be.

Thanks!

Aaron