Conditional probability · Coin flips · difficulty 3 of 5
An even number of flips
You flip a coin that lands heads with probability 0.5, independently each time, until the first heads appears. A friend who watched tells you only that it took an even number of flips in total. What is the probability that it took exactly 2 flips?
Answer with a probability. First lock in a gut guess with an 80% range, then solve it properly, then watch a simulation settle on the truth.
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