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Re: st: probability question


From   Richard Williams <[email protected]>
To   "[email protected]" <[email protected]>, "[email protected]" <[email protected]>
Subject   Re: st: probability question
Date   Wed, 28 Oct 2009 09:32:06 -0500

At 08:22 AM 10/28/2009, 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!

Don't the probabilities change though? e.g. if it rains on the first day, then the probability of rain on the 2nd day is 6/119.

Maybe Maarten can just run a couple million simulations for us...


-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
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