# Puzzle: What is the probability that their other child is also a girl?

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A and B have two children. The probability that the first child is a girl is 50%. The probability that the second child is a girl is also 50%. A and B tell you that they have a daughter.

What is the probability that their other child is also a girl?

posted Jan 14, 2014

+1 vote

the probability is 1/3, about 33%

answer Jan 15, 2014
+1 vote

Possible combinations of kids for A and B -

``````Boy and Girl
Girl and Boy
Girl and Girl
Boy and Boy
``````

Now A&B told that they have a daughter so 4th option is ruled out. Now you have 3 cases and one favorable case i.e. (Girl + Girl) so possible probability is 1/3.

answer Jan 15, 2014

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