#12
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Re: probably a super easy question
All these answers under 50% have to be wrong, right? That can't be right, the 10 red ball bag has to be more likely than the 5/5 bag.
This is a Bayes Theorem issue, so: Event A = the bag is the 10 red ball bag Event B = 2 red balls picked P(B|A) = 1 (only red balls in this bag) P(A) = .5 (either bag equally likely) P(B) = 15/20*14/19 = .55263 (I'm not entirely sure about this one...it might also be .5*(1^2+.5^2)=.625) So P(A|B)=1*.5/.55263=90.476% Or 1*.5/.625=80% (I think this is it actually) If I'm wrong it's probably about P(B), but I'd say the answer has to be above 50%. Edit: Nevermind, I didn't realize that the bag was spun twice [img]/images/graemlins/smile.gif[/img] Bruce already did it. |
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