A coin is biased so that it has a 70% chance of landing on heads. If it is thrown three times, find the probability of getting
a) 3 heads
b) 2 heads and a tail
c) At least 1 head
Probability
2010-12-13 6:07 am
回答 (1)
2010-12-13 6:16 am
✔ 最佳答案
a)P(3 heads)= 70% x 70% x 70%= 0.7 x 0.7 x 0.7= 0.343b)P(2 heads and a tail)= P(HHT) + P(HTH) + P(THH)= 0.7 x 0.7 x 0.3 + 0.7 x 0.3 x 0.7 + 0.3 x 0.7 x 0.7= 3 (0.7 x 0.7 x 0.3)= 0.441c)P(At least 1 head)= 1 - P(All are tails)= 1 - 0.3 x 0.3 x 0.3= 0.973
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