441.Air and Water Before Fire
★★★classical probabilityCh. 2 — Axiomatic and Conditional Probability444+ Problems in Probability
Four cards labelled water, earth, fire, and air lie face down. You flip them over one at a time in uniformly random order. You win if both the air and water cards are revealed before the fire card. What is the probability that you win?
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The earth card is irrelevant. Where must fire sit among the three cards that matter?
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