[Sevenfold]

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What is it about one condition- being forced to exposed losers only- that makes the probabilities different in the end result?

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Player needs ace to win.

Player picks a card.

You randomly expose all but one.

Just ace and 5 are left.

This is 50/50.

What we are forgetting is 80% of the time the game ends when we expose the ace.

So---of the 20% of the time we randomly expose cards and no ace appears, we are 50/50 by switching.

If we look at the cards, the game is always played out, and the ace is on our side 90%.

So, by not looking at the cards, game ends 80% of the time.

So from this point ---the 20% played out with no ace---10% he has ace, 10% the other card, we are 50/50 (10% of 20%).

If you want to make more conditions, the ace and 5 both play say, then the game ends every time those cards are exposed.

So of the times that only the 5 and ace are left , it is 50/50.