1. The problem statement, all variables and given/known data This was an example given in class but I didn't understand how the answer was derived. Suppose we draw 3 balls without replacement from an urn with 2 red, 2 green, and 2 blue balls. Define the following random variables: R = number of red balls drawn G = number of green balls drawn B = number of blue balls drawn What is the probability mass function of R? 0 -> 24/120 1 -> 72/120 2 -> 24/120 2. Relevant equations 3. The attempt at a solution I don't understand how to get those ratios. For 0 red balls, there will be either 2G 1B or 2B 1G.