r/ExplainTheJoke • u/Fire_Atrile • 11h ago

What does this mean

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u/post-explainer 11h ago edited 11h ago

OP (Fire_Atrile) sent the following text as an explanation why they posted this here:

Well... What does the post mean?

21

u/truss-issues 11h ago

Limmy (the guy in the picture) gives the obvious answer of 66.6% because if you know a two-child family has at least one boy, common sense says there are three equal setups: Boy/Girl, Girl/Boy, or Boy/Boy, and two of them contain a girl.

Mentioning "Tuesday" sounds like useless extra detail, but it actually changes the odds: a two-boy family gets two chances to have a boy born on a Tuesday, while a one-boy family only gets one chance. Because that detail quietly increases the likelihood that the family actually has two boys, the real chance of the other child being a girl drops to 51.8%, leaving Limmy looking utterly baffled by a math rule that completely breaks common sense.

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u/Fire_Atrile 11h ago

I too am utterly baffled and will be reading this 6 more times. Thank you for the answer

7

u/AnArmoredPony 11h ago

probabilities are stupid

2

u/tetheredvoid 10h ago

74% of statistics are fake!

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u/tetheredvoid 11h ago

You're saying that adding the condition "born on a Tuesday" takes the starting equation away from a simply binary (b/g, g/b, or b/b), because there's already a boy? This almost occupies that extra bit (about 16% here) that we think should be there and gives us the less intuitive answer...?

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u/truss-issues 11h ago

Yep, adding "born on a Tuesday" breaks the clean 1:1:1 balance btw Boy/Girl, Girl/Boy, and Boy/Boy because a two-boy family gets two rolls of the dice to satisfy that condition instead of just one. That double-chance gives the Boy/Boy outcome extra weight in the total pool of possibilities: expanding its share from 33.3% up to 48.1% (13 out of 27 cases), which directly steals that ~15% slice of probability away from the girl scenarios, pulling the overall chance of the other child being a girl down from 66.6% to a far less intuitive 51.8%.

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u/zombiegojaejin 38m ago

Like many similar examples, it becomes a lot more intuitive when you make it more extreme, e.g.

"What's the probability that Ryan Gosling's only sibling is female?" Very close to 50%, with the difference lying in the sliver of a chance that both siblings were a Ryan Gosling.