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beppe · 06-10-2010, 01:26 AM

Without any information we have

2B = 0.25
BG+GB= 0.5
GG=0.25
(the second is independent from the first one so we can add)

with the knowlege that one at least is a boy
we have to take away GG and renormalize to 1 so I divide for =.75. This gets
BB=1/3
BG+GB =2/3
GG=0

Tuesday has nothing to do with it (it would have been like asking is one of your boys left handed? or with blue eyes, or sleeps at night?)
so the probabilities remain the same.

06-10-2010, 01:26 AM	#9
beppe Grand Sorcerer Posts: 5,161 Karma: 81026524 Join Date: Feb 2010 Location: Italy Device: Kindle3, Ipod4, IPad2	Without any information we have 2B = 0.25 BG+GB= 0.5 GG=0.25 (the second is independent from the first one so we can add) with the knowlege that one at least is a boy we have to take away GG and renormalize to 1 so I divide for =.75. This gets BB=1/3 BG+GB =2/3 GG=0 Tuesday has nothing to do with it (it would have been like asking is one of your boys left handed? or with blue eyes, or sleeps at night?) so the probabilities remain the same. Last edited by beppe; 06-10-2010 at 01:29 AM. Reason: adding reason for adding