Probability of selecting three of the same thing from a collection Question: A collection of 6 items is to be randomly drawn from a bin containing 100 good items and 8 
defective items. What is the probability that exactly 3 of the items chosen are defective?
My Attempt: Well we know that in total there are 108 items. We know that you have a 8/108 chance of the first item being a defective one. I don't understand however, how we can figure out the other items, because it's dependent upon whether the first one was defective or not.
If anyone could explain this, I would greatly appreciate it.

The number $X$ of the defective items in the sample followes the hypergeometric distribution with parameters $N=108$ (population size), $K=8$ ("successes" in the population) and $n=6$ (sample size). Thus $$P(X=3)=\frac{\binom{8}{3}\binom{108-8}{6-3}}{\binom{108}{6}}$$
