Statistics Problem #2
2011-03-05 9:19 pm
Three people toss a fair coin and the odd man pays for coffee. If the coins all turn up the same, they are tossed again. Find the probability that fewer than 4 tosses are needed.
回答 (1)
2011-03-05 9:32 pm
✔ 最佳答案
In each game, the probability that no people needs to pay for coffee if and only if the result is either HHH or TTT with probability 1/4.Let X be the no. of games. Then X ~ Geo(3/4)
P(X < 4)
= F(3)
= 1 - (1 - 3/4)^3
= 63/64
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