June 10th, 2009, 02:37 AM  #1 
Newbie Joined: Jun 2009 Posts: 2 Thanks: 0  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! 
June 10th, 2009, 03:18 AM  #2 
Newbie Joined: Jun 2009 Posts: 3 Thanks: 0  Re: Probability
i would say 1/3 P(A_dies)/P(A_or_B_dies) 0.1/(0.1+0.2) 
June 10th, 2009, 03:10 PM  #3 
Newbie Joined: Jun 2009 Posts: 2 Thanks: 0  Re: Probability
Thanks 100dollars So does this mean you've interpreted "one dies" as "one or both die"? 
June 11th, 2009, 04:51 AM  #4 
Newbie Joined: Jun 2009 Posts: 3 Thanks: 0  Re: Probability
no. i interpreted it 'if only one dies'. event : A or B dies P(A U B) = 0.3 P(AA 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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