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A man visits a couple who have 2 children. one of the children, a boy, comes into the room. find the probability p that the other is also a boy.
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A man visits a couple who have 2 children. one of the children, a boy, comes into the room. find the probability <math>p</math> that the other is also a boy.
  
(a)1/3 (b)2/3 '''(c)1/2''' (d)3/4
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(a)1/3  
  
===Solution===
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(b)2/3  
Since, it's given that the first one is a boy, the second event is independent of the first and the probability is 1/2. Had it been "one of the children is a boy" instead of "first one is a boy" then the probability of two children being boys would have been 1/3 (sample space BB, BG, GB).
 
  
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'''(c)1/2'''
  
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(d)3/4
  
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==={{Template:Author|Arjun Suresh|{{arjunweb}} }}===
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Since, it's given that the first one is a boy, the second event is independent of the first and the probability is 1/2.(The sample space contains only the events concerning the second child ({G, B}) . Had the question been "what's the probability of both the children coming to the room being boys given that one is surely a boy", then the sample space will contain BB, BG and GB and probability would be 1/3)
  
<disqus/>
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{{Template:FBD}}
  
[[Category: Probability]]
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[[Category: Non-GATE Questions from Probability]]

Latest revision as of 11:52, 15 July 2014

A man visits a couple who have 2 children. one of the children, a boy, comes into the room. find the probability <math>p</math> that the other is also a boy.

(a)1/3

(b)2/3

(c)1/2

(d)3/4

Solution by Arjun Suresh

Since, it's given that the first one is a boy, the second event is independent of the first and the probability is 1/2.(The sample space contains only the events concerning the second child ({G, B}) . Had the question been "what's the probability of both the children coming to the room being boys given that one is surely a boy", then the sample space will contain BB, BG and GB and probability would be 1/3)




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A man visits a couple who have 2 children. one of the children, a boy, comes into the room. find the probability p that the other is also a boy.

(a)1/3 (b)2/3 (c)1/2 (d)3/4

Solution[edit]

Since, it's given that the first one is a boy, the second event is independent of the first and the probability is 1/2. Had it been "one of the children is a boy" instead of "first one is a boy" then the probability of two children being boys would have been 1/3 (sample space BB, BG, GB).





blog comments powered by Disqus