Given: 40 blue marbles, 40 red marbles, 20 green marbles
60 are big

If 3 marbles are chosen at random without replacement what is the probability of choosing 3 big blue marbles?

The problem here is that we don't know how many big blue marbles there are in the first place. Do they give you any other data, such as telling you that the big marbles are randomly distributed among the 3 colors? Otherwise it is impossible to give an answer to this question. Please type out the question exactly as it is written in your homework assignment - don't paraphrase.

It is a study guide question and that is the way it was worded and the at is what was confusing me. I wasn't sure if I was supposed to take 60 percent of each or what, but thank you.