I'm trying to figure out the probability of at least one green question being asked in a series of 4 questions. Order has no influence. There are 23 red questions and 14 green questions (total of 37). There are always 4 questions in a row, but, once any question is asked once, it will not return again (this is where I get stuck).
How should I approach this and how do I take into account that a question is never asked twice?
My current reasoning is this:
How should I approach this and how do I take into account that a question is never asked twice?
My current reasoning is this:
- The only option that does not have at least one green question, is the option where all questions are red
- Therefore the chance that at least one question is green, is 1 - the chance that all questions are red
- Every question can only be used once
- So the chance that every question is red is (23 / 37) * (22 / 36) * (21 / 35) * (20 / 34) = 0,13
- So the chance of at least on question being green is 1 - 0,13 = 0,87 (?)