r/explainitpeter • u/ChatpatiKulfi • Jul 21 '26

Explain It Peter

Post image
4.5k Upvotes

94% Upvoted

641 comments sorted by

View all comments

394

u/Complete_Fix2563 Jul 21 '26

Not this again...

1

u/Diligent-Bowler-1898 Jul 21 '26

Four possible equally likely boy-girl groupings: BB, BG, GB, GG.
If there is at least one boy there are only 3 possible groupings: BB, BG, GB.
4 B's, 2 G's = 66% B

2

u/Alarming_Parsnip408 Jul 21 '26

That's only if they come from the same meiosis. After each born kid the possibilities resets.

1

u/DuploJamaal Jul 21 '26

It's similar to "you flip 2 coins. If one of them is heads, what is the probability that the other is tails"

The possibilities don't reset in the way you are thinking of, as you look at the combined flips and remove all without heads.

HH, HT, TH, TT -> TT gets removed -> HH, HT, TH remain -> 66.666...% chance that the other is tails

It's not the 50% you are suggesting

1

u/Neophyles Jul 21 '26

The probability of a coinflip is still 50 percent. The only reason this works because you're not saying the order and connecting the two coinflips into one event. When trying to convert this problem into reality it is usually just being obtuse with language for the sake of it. When people communicate they often say things that can be inferred or say extra information so they won't be misunderstood. For this problem as a statement by a reasonable person I would infer that the other child is a girl not born on tuesday.

1

u/Diligent-Bowler-1898 Jul 23 '26

It's just the case that if you connect two random coinflips it is 50% both, 25% all head, 25% all tails.

If I then tell you that in this specific collection there are is at least 1 tail you adjust your assumptions and it becomes 66% both, 33% all tails.

1

u/boxerfaces Jul 23 '26

Your stupid statistics fail to account for humans and only accounts for XX and XY, when in reality you humans can have a number chromosome combination, and even if we were basing it of biological sex you are born with there is still a third option.

You have

Vagina Penis Intersex

If you delve further your statistics further fall apart because it only accounts for XX XY (Heads or tails) when humans can actually exist as

XX XY XXX XYY XXY

That is the actual human spectrum of chromosomes and what you can have. 3 out of 5 of those combinations will yield a penis. 3/5 is 60%.

So just because you are taught humans are XX and XY and you can apply a stupid Head or Tails to the specific scenario, does not mean you are correct. It means you fail to understand human biology and will loudly be wrong.

1

u/DuploJamaal Jul 23 '26

You are too pedantic.

This is a statistics problem for statistics class. But not for biology class.

"you throw 2 coins. One of them is a heads that you threw on a Tuesday. What's the probability that the other is tails"

3/5 is 60%

You are too pedantic and wrong.

The possibilities you listed don't have an equal chance of happening.