How do you find equally likely possibilities?

#1
I have attached a homework problem to this post. It asks what the probability is that all 4 watches of a selection are inaccurate when the manufacturer claims that .05% of all its watches are inaccurate after a year. This is where I get so tripped up, I know that Probability is # of possibilities that meet my conditions/# of equally likely possibilities but I can't come up with what the equally likely possibilities are.

This is my thought process so far - 5 of 100 watches will be bad. So I need to find what the likelihood of selecting 4 of those 5 is? I am over thinking this I am sure. Is there an equation I should be using? Any help is greatly appreciated.

I completely understand these problems when someone talks me through them. I don't know why I can't reach a conclusion myself.