why the odds of the “two children problem” are 1/3?

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I was asked the question “a man states he has two children, and at least one of them are boys, what are the odds that the man has two boys?” I’ve been told the answer is 1/3, but I can’t wrap my head around it. Additionally, there is another version of the problem that states he has at least one boy born on a Tuesday. How does that change the odds? Why?

Edited to add (so people don’t have to sort through replies): the answer is 1/3 because “at least one boy” is accounting for B/G & G/B. The girl can be the first or second child. You can move the odds to 50/50 by rewording the question to “my first of two children is a boy, what are the odds the other child is a boy”

In: Mathematics

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Anonymous 0 Comments

Something worth mentioning that I haven’t seen yet, the reason there are four options is because the actual real-life probability of having two boys or two girls is only 25% (flipping a coin twice). Having one of each is 50%. So it is important to separate these options out when calculating the probabilities. 

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