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From |
Richard Goldstein <richgold@ix.netcom.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: probability question |

Date |
Wed, 28 Oct 2009 09:36:55 -0400 |

thank you! Jeph Herrin wrote: > > Prob(rain) = 7/120 > Prob(no rain) = 113/120 > > X=days it rains on hat > > Prob(X=3)=c(4,3)*(7/120)^3*(113/120)^1 > =4*0.0001985*0.94 > =0.0007477 > > > not much chance! > > > Richard Goldstein wrote: >> it's been a long time since I thought about questions like this, but, as >> a lead-in to a study, a client has asked the following question which he >> thinks he understands and says is related to where he wants to go: >> >> during a consecutive period of 120 days, if it rains on 7 days and my >> client wears a hat on 4 days (these are independent of any knowledge of >> the weather), what is the probability that it will rain on 3 of the days >> on which he is wearing a hat? >> >> my client swears that this is not a homework problem for him or his wife >> or one of their kids! >> >> Rich * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: probability question***From:*Richard Goldstein <richgold@ix.netcom.com>

**Re: st: probability question***From:*Jeph Herrin <junk@spandrel.net>

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