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June 10th, 2009, 02:37 AM   #1
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Probability

Hi, easy question but I need someone to verify that this is right!

The probability that A will die within the next 10 years is 0.1 and the probability that B will die within the next 10 years is 0.2. What is that probability that, if one dies, it will be A?

I used a karnaugh table to work it out, and interpreted "if one dies" as meaning "if only one dies", and my answer was4/13. Is this correct?

Thanks!
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June 10th, 2009, 03:18 AM   #2
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Re: Probability

i would say 1/3

P(A_dies)/P(A_or_B_dies)
0.1/(0.1+0.2)
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June 10th, 2009, 03:10 PM   #3
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Re: Probability

Thanks 100dollars
So does this mean you've interpreted "one dies" as "one or both die"?
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June 11th, 2009, 04:51 AM   #4
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Re: Probability

no. i interpreted it 'if only one dies'.

event : A or B dies P(A U B) = 0.3

P(A|A U B) = P(A intersection (A U B)) / P(B) = P(A) / P(B) = 1/3

// EDIT: maybe you are right. i didnt consider the event that both of them dies.
then having a state space (A_dies, B_dies, A_and_B_dies) = (0.1 , 0.2, 0.02 )

then P(A_dies) / P(A_dies U B_dies U A_and_B_dies ) = 0.1/(0.32) = 10/32 = 5/16

what do you think? Write your solution
Just one question. This has to do with statistics class right? Because t is written in a way so typical for statistics exercises, where if you only studied probability theory, you really have a hard time finding yourself in it.
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