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Got into a debate over when a deck of cards drawn without replacement is dependent. My opinion is that when there is no replacement, it is always dependent. That even before you draw the first card, you know already what the odds are.

My "esteemed colleague" (I think he's nuts) believes it is only when you know what the first event is. The following is his argument.

<quoting>

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My argument is that until there is information on what any of the initial cards are, all of the cards in any of the positions are independent. As soon as any information is available on the initial cards, they become dependent.

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</quoting>

I prefer to draw a tree diagram to map out what the chance of an event is.

The question that sparked this was "What is the probability of the second card drawn without replacement from a 52-card deck being a spade?"

My friend thinks that without any information the first card has no influence on the odds of getting a spade, and is independent. That if you were to pick out the second from the top (The one that would be drawn in the second event) the probability is 1/4 that it is a spade, because you don't have information on the first trial.

My apologies if I was a bit odd with my post. Its very late. :zzz: and I think all the arguing has gotten both me and my friend confused.