h********2
发帖数: 23 | 1 Blook has done a nice job of combing a number of 合集 tonight. It took a
while to go through them with all the discussion on each post. I compiled
them and try to put answers immediately after each question that I believe
is right.
In discussion follows, please always indicate the problem # being discussed.
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Question 1.
You have a fair coin. Calculate the expected number N of throws
that you need to find two HH at the end of sequence?
A:
For the first one, | f****e
发帖数: 590 | 2 求Question 11第二种解法的解释（关于time reversible markov chain）
discussed.
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【在 h********2 的大作中提到】
: Blook has done a nice job of combing a number of 合集 tonight. It took a
: while to go through them with all the discussion on each post. I compiled
: them and try to put answers immediately after each question that I believe
: is right.
: In discussion follows, please always indicate the problem # being discussed.
: ☆─────────────────────────────────────☆
: Question 1.
: You have a fair coin. Calculate the expected number N of throws
: that you need to find two HH at the end of sequence?
: A:
| b******w
发帖数: 52 | 3 Question 1.
You have a fair coin. Calculate the expected number N of throws
that you need to find two HH at the end of sequence?
A:
For the first one, use the conditional probability.
Let Y be the number of throws in the sequence.
Case I: the first throw is a Tail, prob = .5
Case I: the first throw is a Head and the 2nd throw is also a H, prob = .25
Case II: the first throw is a Head but the 2nd is a Tail, prob = .25.
E[Y] = .5 *(1+E[Y]) + .25 * 2 + .25 * (2+E[Y])
solve it and get E[Y] = 6
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