Question 1164268
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There are 2*2*2 = 8 possible boy/girl sequences.<br>
Of those 8, only two are sequences in which the birth order alternates between boys and girls: BGB and GBG.<br>
Of those two, only one has a boy as the youngest.<br>
ANSWER: The probability that the youngest is a boy, given that the birth order alternates between boys and girls, is 1/2.<br>
More formally, using the definition of conditional probability, theprobability that the youngest is a boy, given that the birth order alternates between boys and girls, is:<br><pre>
 P((birth order alternates between boys and girls)AND(youngest is a boy))    (1/8) =  1
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           P(birth order alternates between boys and girls)                  (2/8) =  2