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A girl you like tells you that there's a $1$% chance she'll go out on a date with you. What is the expected number of times you have to ask her out before you get a date?

(Not a homework problem - I figure it's like flipping a coin with $99$% heads, $1$% tails, stop flipping when you get a tail.)

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    Is that girl really worth it? Just for a date? ;p2011-02-08
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    On the other hand, I once thought about a variant of this game: suppose we're not really interested in that one specific girl, but only interested in assessing the probability one can pick up a girl. Now, since each time you succeed or fail, we can assume you have learned something, the probabilities will not be constant over time but will have to be updated. That seems like more interesting to model, although still a bit too general. We have to narrow it down to some specific Bernoulli model for individual dates with a set rule for updating its probability.2011-02-08
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    Since we don't yet know the motivation behind the question, we must add the caveat of "restraining order" at question $N$, where $N$ is a positive integer that is determined empirically, varies slightly from girl to girl and is directly proportional to age. In the U.S., $N$ is approximately $5$, so I'd say if $p$ is less than $20$%, then $5$ times is the expected number of questions. Otherwise, the expected number of questions is $\infty$ _from a jail cell_.2011-02-08
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    I think she's just saying that to get you to ask her out 100 times. I'd go for someone else if I were you.2011-02-08
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    If the girl gets to know this, then your probability will probably drop down further to 0%. But still it doesn't mean you will never get a date, though it means your expectation becomes $\infty$2011-02-08
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    Reminds me of this: http://movieclips.com/LpKN-dumb-and-dumber-movie-theres-a-chance/2011-02-08
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    I can't see the above from my country, but is it related to: "It's 50% chance you'll follow me home. Either you do or you don't."? Might work on uneducated targets though... ;-)2011-02-11
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    I have decided to protect this question. In the past 2 hours we have had at least three pointless answers added. Besides, I really wanted to try the protect feature out :-)2011-02-12
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    @Marcus: that's a shame!2011-02-12
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    @Moron: Dear Moron, thank you for doing this.2011-02-12
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    @Akhil: You are welcome :-)2011-02-12
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    Looking at the number of views this question has got, one learns how important it is to choose the right phrasing for a maths problem.2011-02-12
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    This reminds me of a test question a friend had: "You flip a fair coin. What is the probability you get tail?" In the margins he wrote "0%, because I'm a math major."2012-07-23

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